* Marci can destroy Supernova by herself with Unleash at any stage of the game.
* Phoenix is squishy hero with low armor and is very vulnerable for Rebound and Sidekick at the laning stage.

* Rebound allows her to jump in or out of the Arena Of Blood. She can save her allies from the Arena with Dispose as well.

* Corrosive Skin gives Viper additional resistance to Phoenix's magical damage, and since they deal damage over time, Phoenix would be constantly afflicted by his passive's own debuff, making him not an ideal target for Phoenix's harassment. Phoenix's abilities also constantly drain its own health away, becoming more vulnerable to Poison Attack.

* Nethertoxin breaks the damage block from Bulwark.
* Poison Attack and Viper Strike's slows make it difficult for Mars to contribute to fights due to his low mobility.
Additional:
* Viper Strike can disable Bulwark entirely, making Mars far less tanky. Using Nethertoxin inside Arena of Blood may discourage enemies from following up with Mars's initiation.
* Rod of Atos is currently common on Viper and keeps Mars in position long enough to be killed.
* However, Viper is not very tanky earlier in the game, so positioning against Mars is important for Viper since a well-timed Spear of Mars can be the end of Viper.

* Phoenix constantly depletes its own health due to the health costs of its abilities. Unlike heroes that have a similar mechanic, Phoenix does not benefit from low health, nor does it really have a countermeasure for it. As such, Phoenix is a very vulnerable target for Necrophos to prey on, especially when caught off guard before it can cast Supernova.
Additional:
* Necrophos becomes a bigger threat the lower one's health gets, and unfortunately for Phoenix, most of its spells have noticeable health costs. Those costs, coupled with his Heartstopper Aura, means that staying in a teamfight for too long under Necrophos' presence will make Phoenix a more valid target for his ultimate, with its stun completely preventing any form of retaliation or protection. Necrophos players are also likely to buy more durability items such as Hood of Defiance, making him more able to withstand Phoenix's damage despite having no escape mechanisms.
* However, it is also important to remember that a Scepter-upgraded Supernova can help protect an ally from his ultimate.

* Necrophos' largely magical damage completely ignores Bulwark.
* Ghost Shroud protects Necrophos from God's Rebuke but more importantly stops Mars from being a threat in lane.

* Huskar's high attack speed can counteract Fire Spirits, and easily destroy the Supernova.
Additional:
* Berserker's Blood will let Huskar easily face down a Supernova with increased attack speed.
* Icarus Dive may not be an easy escape from Huskar either as he can chase Phoenix during it with Life Break if Huskar times it right.
* However, Phoenix can buy items which can

* Burning Spear's magical damage is very troublesome for Mars in the laning stage.
* Life Break's percentage-based magical damage bypasses Bulwark, and can also be used to jump in or out of Arena Of Blood.

* Phoenix does significant magic damage over time which can either be dispelled or negated by Fate's Edict.
* Oracle's burst damage potential can prove lethal to Phoenix, as they already have to sacrifice health to cast their basic skills.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Ursa can easily unleash a number of attacks in an incredibly short amount of time, easily destroying the Supernova in a couple of seconds regardless of Fire Spirits' debuff. His Enrage also dampens any damage Phoenix might toss at his direction, as well as remove any debuffs Phoenix may place on him.

* Ursa is a special mention because despite Bulwark diminishing most of the damage Ursa does, he is quite durable, especially with Enrage, discouraging the aggressive all-in playstyle of Mars; Ursa can simply not target Mars.

* Heroes with spell immunity-granting spells will render Phoenix useless against them, as Phoenix has almost no spell immunity-piercing ability, other than the stun at the end of Supernova: Lifestealer, Juggernaut.

* Rage, acting as a pseudo-Black King Bar, completely negates Mars' initiation if used in time.
* Feast does damage and heals based on max health, perfect against high-health strength heroes like Mars.
* Infest allows Lifestealer to potentially save allies from Mars' initiation with a quick burst of extra health.

* Any hero with high attack speed will be a threat to Phoenix when it initiates, as they can easily tear down a Supernova, perhaps even while debuffed by Fire Spirits: Juggernaut, Clinkz, Troll Warlord, Beastmaster, Lina.

* Dragon Slave deals reliable magic damage during the laning phase against Mars.
* Lina's Eul's Scepter of Divinity and Light Strike Array combo can interrupt Mars from being disruptive for a decent amount of time and leave him vulnerable for follow up stuns.
* Laguna Blade deals massive magical damage, and pure damage with Aghanim's Scepter.

* Silence (and mana burns) will be a persistent problem for Phoenix, as it is heavily reliant on its abilities whether defensively or offensively, so heroes like Death Prophet, Skywrath Mage, and even Nyx Assassin must be closely observed to prevent being shut down by these heroes.
* Hexes are a greater threat to Phoenix as they also disable items, preventing Phoenix from dispelling the debuff on its own.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Tempest Double, Magnetic Field's attack speed bonus, and Arc Warden's high attack range will easily destroy a Phoenix using Supernova much faster than usual.
* Phoenix is very weak against pushers, especially those like Arc Warden who can kill him easily, as his skillset works best in teamfights.
Additional:
* His Tempest Double is not an illusion, but rather a full hero unit, which effectively reduces half of the Supernova's health. His Magnetic Field can tremendously boost his attack speed, allowing him to destroy Supernova in no time even when he's affected by Fire Spirits.

* Arcane Orb's pure damage ignores Mars' Bulwark.
* Astral Imprisonment can be used to stop Mars from being disruptive or save allies from his abilities.
* Sanity's Eclipse deals high damage to Mars, due to his low intelligence pool.

* Decay, Soul Rip and Flesh Golem all deal magical damage which ignores Bulwark.
* Decay reduces Mars' natural strength and therefore his health pool, which is what he relies on to trade effectively in lane.

* It is difficult for Mars to trade blows with Ogre Magi in the early game thanks to his high base health, resistance and Ignite.
* Bloodlust can assist Ogre Magi or an ally in repositioning against Mars for its move speed bonus.
* Fireblast can interrupt and mitigate Mars from performing his skill combos, especially in combination with Multicast.

* Chemical Rage kills Phoenix very quickly in Supernova.

* Spiked Carapace reacts on any of the damage over time from Phoenix's abilities and can interrupt Sun Ray and Icarus Dive.

* Solar Guardian can save allies caught inside Arena of Blood.

* Silencer will most likely disrupt an initiation with his ultimate, Global Silence, prevent escape with his Last Word, and if Phoenix happens to die to him (or near him) enough times, he would sap enough of Phoenix's much needed Intelligence to make him a stronger foe and Phoenix with less mana than it already had.

* Nether Blast, Decrepify and Life Drain deal high magical damage and bypasses Bulwark.
* Nether Ward reduces the amount of abilities Mars can use during fights and forces Mars to be careful about the heavy mana cost of Arena Of Blood.
* Pugna is one of few heroes that can contest Mars' ability to push and defend towers early on.

* Ball Lightning makes it almost impossible to catch Storm Spirit without someone else initiating for you.
* Overload is not reduced by Bulwark and the magical damage spam can wear down Mars quickly.
Additional:
* Storm Spirit's abilities all do magical damage, which can bypass Bulwark.
* Ball Lightning can escape through Arena of Blood and it is easy to dodge Spear of Mars.

* As a hero with uncommon traits, Phoenix's abilities require more health than mana. It is advised for Rubick to purchase health regeneration items such as Tranquil Boots, Urn of Shadows or Hood of Defiance to keep up with the HP loss.
* Phoenix's signature Supernova, if casted successfully, can turn a teamfight around if being stolen.
* The initial lift and the following crowd control from the drop of Telekinesis can protect the egg from being attacked if casted right before Supernova with quick fingers.
* A successfully reborn Supernova refreshes the cooldown of Telekinesis as well as Fade Bolt, so don't hesitate to spam both of them before Supernova with the reasons mentioned above.
* Supernova has a stun range of 1200, which requires Rubick to have Level 3 Arcane Supremacy at least to exceed its range. Consider buying Aether Lens or Blink Dagger to help with positioning.
* It is not possible to cast Supernova (as of 7.31c) with Aghanim's Shard's extra Sun Ray even with both spell stolen, since Sun Ray takes up two stolen ability slots.
* Icarus Dive is a useful repositioning ability for scouting, initiation or escaping.
* Fire Spirits aids with Rubick farming given enough HP regeneration. In early skirmishes, the stolen ability can slow the attack speed of the enemy team to a crawl.
* Combined with Fade Bolt, both the attack damage and attack speed of the enemy team are reduced if they have no source of dispel, effectively nullifying their physical attack damage.
* Sun Ray thrives in and after a teamfight by damaging enemy heroes and healing allies at the same time.
* Rubick can interrupt both Icarus Dive and Sun Ray by casting Telekinesis.

* Mars' own father is a formidable foe because Zeus deals massive amounts of magical damage. The high damage, low cooldown nukes of Arc Lightning and Lightning Bolt combined with the percent health magic damage of Static Field will shred Mars' health because it bypasses Bulwark completely.

* Although Phoenix has many ways to disable a Blink Dagger, the high cooldown of all of its spells makes them not as reliable for this. Also, its spells cost a lot of health to use, making it easy to get nuked down.
* Waning Rift prevents Phoenix from using Supernova to refresh itself, giving Puck's team time to finish it off, or allow Puck to burst Phoenix down.
* Dream Coil prevents Phoenix from using Icarus Dive without consequences. Waning Rift and Dream Coil are also able to cancel Sun Ray, which is its main source of damage in the late game.

* Snowball can protect Tusk and his teammates from a Spear of Mars' stun after an Arena of Blood, and with proper targeting, even bring them out of the Arena. This is especially noticeable in the earlier stages of the game before allies buy Black King Bar and rely on this less. Even during the late-game, Tusk can purchase a Blink Dagger to save allies that are caught before Black King Bars can be used by Blinking in and Snowballing out.
* Tag Team is a constant threat to Mars in-lane, as it deals significant damage and slow, making Bulwark slightly ineffective.
* It is worth noting that Ice Shards can be detrimental to Tusk's own team by creating terrain that Spear of Mars can latch on, though using it conservatively is a good enough solution in most cases.

* Swashbuckle is an auto attack and therefore ignores Mars' Bulwark.
* Shield Crash upgraded with Aghanim is an auto attack and therefore ignores Mars' Bulwark.
* Rolling Thunder makes him immune to magic, making Pangolier able to roll in and out of Mars' Arena Of Blood.

* Venomancer's spells all deal magical damage, ignoring Bulwark.
* Venomancer's multiple slows are especially effective at kiting Mars.
* Plague Ward can attack through Arena Of Blood.
Additional:
* Venomancer's poison attacks are all magical damage, ignoring Bulwark.
* Venomancer's multiple slows are especially effective against Mars' low mobility.
* Plague Wards can attack through Arena of Blood.

* Lil' Shredder will make quick work of Supernova.
* Mortimer Kisses can easily hit a Phoenix using Sun Ray.

* Inner Beast helps Beastmaster's team destroy Supernova quickly.

* Sticky Napalm slows turn rate, making it difficult for Mars to face frontwards, where Spear of Mars and Bulwark are effective. In combination with Firefly, which deals magic damage, Batrider can make quick work of Mars.
* Flaming Lasso disables Mars while enemies re-position themselves behind Mars to avoid Bulwark.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Heroes that can save their allies can be a big problem for Mars: Dazzle, Omniknight.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Heroes that depend on disrupting fights with ability combos or big ultimate abilities are vulnerable to the long stun of Fiend's Grip: Disruptor, Death Prophet, Enigma, Faceless Void, Invoker, Lich, Magnus, Mars, Medusa, Outworld Destroyer, Phoenix, Puck, Queen of Pain, Shadow Fiend, Treant Protector, Underlord, Winter Wyvern, Witch Doctor, Zeus.

* Heroes that depend on disrupting fights with ability combos or big ultimate abilities are vulnerable to the long stun of Fiend's Grip: Disruptor, Death Prophet, Enigma, Faceless Void, Invoker, Lich, Magnus, Mars, Medusa, Outworld Destroyer, Phoenix, Puck, Queen of Pain, Shadow Fiend, Treant Protector, Underlord, Winter Wyvern, Witch Doctor, Zeus.

* Silence (and mana burns) will be a persistent problem for Phoenix, as it is heavily reliant on its abilities whether defensively or offensively, so heroes like Death Prophet, Skywrath Mage, and even Nyx Assassin must be closely observed to prevent being shut down by these heroes.
* Hexes are a greater threat to Phoenix as they also disable items, preventing Phoenix from dispelling the debuff on its own.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Heroes that can save their allies can be a big problem for Mars: Dazzle, Omniknight.

* Heroes with high magical or pure damage will bypass Bulwark: Timbersaw, Dark Willow, Enigma, Invoker, Pugna, Skywrath Mage, Tinker, Zeus, Oracle.

* Firestorm and Pit of Malice are very disruptive in team fights, completely matching Mars especially since it can all be cast inside Arena Of Blood and also does percentage-based magical damage, negating Bulwark.
* Dark Rift can save any allies of Underlord trapped in Arena Of Blood.
* Atrophy Aura allows Underlord to lane against Mars quite well since he does not have the best base damage during the early game.
* Underlord is a common carrier of both Pipe of Insight and Mekansm/Guardian Greaves, allowing his team to combat Mars in the mid to late game.

* Phoenix's limit AoE, damage-over-time abilities give Io plenty of time to save allies with Relocate.

* Blink Strike gives bonus backstab damage and can bypass Bulwark. Defensively, it could be used to teleport away from Mars, especially while inside Arena of Blood.
* Smoke Screen can interrupt Mars' skill combos, especially when cast inside Arena of Blood.
* Tricks of the Trade can be used to evade Mars' skills, which have a slight delay to them. It could also be used to buy himself time while trapped inside of Arena of Blood.
Additional:
* Bulwark is generally irrelevant against Riki as he primarily deals bonus damage from behind.

* Shadowraze deals magic damage and ignores Bulwark.
* Requiem of Souls deals magic damage and can fear Mars away, forcing him to turn around and therefore become vulnerable.

* Anti-Mage dispels Phoenix's slows with Manta Style.
* Anti-Mage can Blink directly next to Supernova, giving him more time to destroy the egg.

* Song of the Siren does not affect Supernova, which allows her and her team to focus the egg while the enemy team is affected by sleep.
* Phoenix cannot use Icarus Dive for escaping when rooted by Ensnare.
* However, Phoenix has many area-of-effect abilities that allow him to clear Naga Siren's illusions from Mirror Image.

* Legion Commander is both good and bad vs Mars, on the plus side she can dispel Spear of Mars with Press the Attack and is a good Silver Edge carrier. However, Mars is not an ideal Duel target, as Bulwark will force her to 1: Buy Silver Edge, and 2: Hit Mars with it before the Duel, allowing a skilled Mars to react, especially with Eul's Scepter of Divinity. In teamfights, Mars will happily draw attention after using his abilities, and tank the Duel with all spells on cooldown.

* Heroes with blink or movement abilities, which are disabled by Pounce's leash: Anti-Mage, Earth Spirit, Faceless Void, Magnus, Mirana, Monkey King, Morphling, Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, Timbersaw, Tusk.

* Since all of Phoenix's abilities (except for Supernova) have health costs, heroes like Ancient Apparition or Necrophos can turn Phoenix's abilities against it. However, Supernova does completely protect Phoenix from Ice Blast.

* Kunkka's Ghostship and Torrent disrupt fights in Arena Of Blood.

* Heroes with break abilities: Shadow Demon (with Aghanim's Scepter), Viper.

* Nukers who have set amounts of damage will really struggle against Lone Druid especially in True Form: Puck, Void Spirit, Mars.

* Medusa's Stone Gaze forces Mars to choose between getting petrified, or turning his vulnerable back on Medusa.

* Void can interrupt Icarus Dive.
* His Crippling Fear's silence will shutdown a spell caster Phoenix.
* However, Phoenix punishes Night Stalker with Supernova because it will turn night into day, and it has a higher priority than Dark Ascension, effectively canceling the passive bonuses Night Stalker gets from Hunter in the Night.

* Time Dilation while Spear of Mars and God's Rebuke are on cooldown will make these abilities unusable for a long time, rendering Mars nearly useless.
* Mars cannot turn inside the Chronosphere, which makes it easy to attack him from the back, bypassing Bulwark completely.
Additional:
* Time Walk allows Faceless Void to escape or enter Arena Of Blood, and helps him recover from Mars' burst damage.
* Time Lock's magical damage ignores Bulwark.
* Chronosphere allows Faceless Void to reposition behind Mars, ignoring his Bulwark while he is helplessly frozen in time.

* Any hero with high attack speed will be a threat to Phoenix when it initiates, as they can easily tear down a Supernova, perhaps even while debuffed by Fire Spirits: Juggernaut, Clinkz, Troll Warlord, Beastmaster, Lina.

Additional:
* Due to Fervor and Battle Trance, Troll Warlord is one of the best heroes to deal with Supernova.

* Juggernaut's high attack speed lets him destroy a Supernova easily. He can even attack a Supernova during Blade Fury with his regular attacks.
* Blade Fury protects Juggernaut from all of Phoenix's spells (except Supernova, which pierces spell immunity).
* Blade Fury can also dispel the attack speed slow from Fire Spirits and the movement speed slow from Icarus Dive.
* Phoenix's Icarus Dive will not protect it from Omnislash unless it dives into creeps, and Phoenix's low armor makes for an easy kill.

* Earthbind can prevent Phoenix from using Icarus Dive, the only escaping mechanism of this hero.
* Heavy burst damage from Poof can easily kill Phoenix even when it slows down all the Meepos with Fire Spirits.
* Meepo's clones destroy the Phoenix Sun from Supernova in no time, even when they are slowed down by Fire Spirits.
* Meepo's naturally high magic resistance gives Phoenix a hard time with bursting him down. He can even turn the tide if Icarus Dive is on cooldown.
Additional:
* Meepo is unlike any other multi-unit enemy Phoenix may face in the battlefield. Unlike illusion-based heroes like Phantom Lancer or Chaos Knight, Meepo's clones are not illusions, meaning they can deal full damage to the Phoenix Sun if all four (or five) are present.

* Any hero with high attack speed will be a threat to Phoenix when it initiates, as they can easily tear down a Supernova, perhaps even while debuffed by Fire Spirits: Juggernaut, Clinkz, Troll Warlord, Beastmaster, Lina.

* Phoenix expends health to use its abilities, making it a good target for Thirst.
* Rupture deals heavy damage against Icarus Dive.
Additional:
* Although Blood Rite can be easily avoided, if it does hit, its lengthy silence and pure damage can be a severe punishment for a slow, unobservant, or simply unfortunate Phoenix.
* His Rupture can turn Icarus Dive into a suicide option, and it cannot be dispelled, meaning even if Phoenix completes a Supernova, choosing to Dive may just cut its health back down.
* And finally, due to Phoenix's health costs, too much careless ability spamming may just put Phoenix into Bloodseeker's vision through Thirst, making it a very tempting ganking target.

* Berserker's Call forces Mars to face in the direction choosen.
* Counter Helix deals pure damage and can go through Bulwark.

* Heroes that deal damage over time will also fail to bring down Abaddon and his allies, such as Huskar, Venomancer, or Phoenix.