Dazzle
* 
Juxtapose and 
Doppelganger conjures too many illusions for Dazzle to deal with, given he has no inherent movement- or AoE-abilities.
* 
Phantom Rush and 
Spirit Lance allow Phantom Lancer to trivially catch Dazzle even in the back line of a fight.
* Phantom Lancer has high base armor which counters Dazzle's physcial damage based spells in lane.
Keeper of the Light
* Heroes with dispels: 
Legion Commander, 
Oracle, 
Slark, 
Phantom Lancer
Dazzle
* Heroes with high burst damage through their physical attacks or spells can kill Dazzle or his allies before he has a chance to use Shallow Grave. (
Lina, 
Lion, etc.)
Keeper of the Light
* 
Finger of Death can instantly shred many targets, especially fragile Heroes like 
Keeper of the Light, 
Ancient Apparition or 
Bounty Hunter.
Keeper of the Light
* 
Crippling Fear prevents Keeper of the Light from using his spells to keep his team alive during team-fights.
* 
Dark Ascension is very strong against Keeper of the Light, as it allows Night Stalker to jump the backline and quickly kill the squishy Ezalor, especially when combined with the slow from 
Void.
Additional:
* Keeper of the Light's 
Aghanim's Scepter upgrade loses much of its power, due to Night Stalker being able to reduce the duration of daytime by a lot.
Dazzle
* 
Astral Imprisonment is a versatile nuisance:
* If it is cast on a low-enough-health unit at least 1 second into Shallow Grave's duration, the Shallow Grave will end during the imprisonment, and the target will take lethal damage when released.
* It can be used remove Dazzle from the fight at a time he could have saved someone.
* It lets himself or an ally dodge all of Poison Touch's effects, for long enough to recover their 
Blink Dagger.
Keeper of the Light
* 
Spiked Carapace can be used to reflect Illuminate damage and stun Keeper of the Light.
* 
Vendetta allows Nyx Assassin to follow Keeper of the Light around if he tries to split-push.
* Keeper of the Light is very squishy and will very quickly die to Vendetta and it's followup abilities.
Dazzle
* 
Shallow Grave prevents Ice Blast's shatter for up to 5 seconds, but can mostly only delay it as Ice Blast's debuff lasts 10 seconds and prevents 
Shadow Wave from healing them.
Additional:
* 
Ice Blast negates healing from Shadow Wave, and lasts longer than Shallow Grave.
Dazzle
* Culling Blade ignores the protection from Shallow Grave and will kill any target whose health is low enough. This makes Axe one of the hardest counters to Dazzle, and he neutralizes one of Dazzle's most important abilities.
Additional:
* 
Culling Blade kills any target under the health threshold, even through Shallow Grave.
Keeper of the Light
* 
Rage allows him to be immune to all of Ezalor's abilities. Also, the increased movement speed combined with the slow from 
Ghoul Frenzy and the squishy nature of Ezalor allows Lifestealer to take him down very quickly.
Dazzle
* Doom can completely shut down Dazzle through 
Doom, as it prevents him from casting his abilities and, by extension, gaining Bad Juju stacks.
Keeper of the Light
* Heroes with silences: 
Puck, 
Doom, 
Riki.
Dazzle
* Heroes with the ability to heal allies, or those with good defensive abilities: 
Chen, 
Dazzle, 
Io, Oracle, 
Omniknight, 
Witch Doctor, 
Winter Wyvern, 
Abaddon, etc.
Keeper of the Light
* Heroes with dispels: Legion Commander, Oracle, Slark, Phantom Lancer
Dazzle
* Some heroes with extreme range, like 
Zeus, 
Invoker or 
Clockwerk, can snipe your allies from anywhere after your Grave has expired.
Dazzle
* Some heroes with extreme range, like Zeus, Invoker or Clockwerk, can snipe your allies from anywhere after your Grave has expired.
Keeper of the Light
* Jakiro's reliance on his abilities can cause struggles for heroes who rely on evasion or blinds to get upper hand: 
Phantom Assassin, 
Windranger, Riki, 
Troll Warlord, Keeper of the Light.
Keeper of the Light
* Heroes with silences: Puck, Doom, Riki.
Keeper of the Light
* Heroes that can jump and kill him: 
Meepo, 
Clinkz, 
Templar Assassin
Keeper of the Light
* Heroes with hastes: 
Dark Seer, 
Lycan
Dazzle
* Spectre's entire ability set is designed to get to and destroy heroes that stay in the backlines, both carries (like the aforementioned 
Drow Ranger and 
Sniper) and supports (like Dazzle and 
Shadow Shaman).
Keeper of the Light
* Heroes with teleports to escape Solar Blind and Will-O-Wisp: Phantom Assassin, Puck, 
Queen of Pain, 
Storm Spirit
Keeper of the Light
* Heroes with channeling abilities: 
Enigma, Witch Doctor, 
Crystal Maiden.
Dazzle
* 
Bloodseeker's 
Thirst, 
Rupture, and huge AoE silence 
Blood Rite can fare well against Dazzle.
Keeper of the Light
* Blood Rite makes Ezalor chose between getting off Illuminate or getting silenced for a while, as Illuminate is a channeled ability.
* Blood Rite's silence can completely take Ezalor out of a teamfight, as he relies on his abilities to be useful.
* Keeper of the Light's only mobility source, his high movement speed (via his high base movement speed and through spirit form), is entirely countered by Rupture.
Dazzle
* Shallow Grave prevents Bloodseeker from replenishing his health by finishing off enemies.
Keeper of the Light
* Heroes that can jump and kill him: Meepo, Clinkz, Templar Assassin
Dazzle
* Heroes with high burst damage through their physical attacks or spells can kill Dazzle or his allies before he has a chance to use Shallow Grave. (Lina, Lion, etc.)
Additional:
* Laguna Blade can kill Dazzle quickly before he casts Shallow Grave.
Keeper of the Light
* Heroes with silences: Puck, Doom, Riki.
Keeper of the Light
* Heroes with teleports to escape Solar Blind and Will-O-Wisp: Phantom Assassin, Puck, Queen of Pain, Storm Spirit
Keeper of the Light
* Heroes with channeling abilities: Enigma, Witch Doctor, Crystal Maiden.
Keeper of the Light
* Squishy heroes, usually supports, like Lion, Ancient Apparition, Keeper of the Light etc can die quickly to Tiny's magic burst.
Dazzle
* Dazzle's lack of a true disable makes him a relatively vulnerable target for Phantom Assassin.
* Coup de Grace will often kill Dazzle's teammates before he has a chance to use Shallow Grave.
Keeper of the Light
* Heroes with teleports to escape Solar Blind and Will-O-Wisp: Phantom Assassin, Puck, Queen of Pain, Storm Spirit
Dazzle
* Doom, 
Disruptor with Aghanim's Scepter, Dazzle with 
Aghanim's Shard, and hex abilities all prevent item usage, which is a severe problem for Phantom Assassin as it prevents her from using 
Black King Bar, the one item that helps protect her against the aforementioned dangers. Doom and 
Shadow Demon with Aghanim's Scepter also disables Phantom Assassin's Evasion and Critical Strike, removing much of her damage and survivabaility.
Keeper of the Light
* Heroes which rely exclusively on right clicks will struggle somewhat against Blinding Light: Phantom Assassin, 
Wraith King, 
Medusa
Keeper of the Light
* Being an intelligence caster hero, Ezalor usually has a high mana pool and low health and armor, making him a prime target for 
Mana Void
* Ezalor's Illuminate damage and Solar Bind's magic resistance reduction are greatly reduced thanks to 
Counterspell. Counterspell can also block and reflect Solar Bind if timed properly.
* Anti-Mage usually is not hampered by Solar Bind or Will-O-Wisp thanks to 
Blink.
* However, despite all of this, if Keeper of the Light is played carefully and tops off his team's mana at all times, Anti Mage will not be able to get off a good Mana Void.
* By the same token once Keeper of the Light gets a 
Octarine Core, he can spam Charka Magic to keep his own mana full
Keeper of the Light
* Keeper of the Light can stall pushes with 
Illuminate. This makes him strong against pushing heroes: 
Terrorblade 
Naga siren 
Nature's Prophet and 
Anti-Mage
Dazzle
* Shallow Grave can be used to save an ally whom Terrorblade has used 
Sunder on under the condition Dazzle is quick enough to do it.
* 
Poison Touch upgraded with Aghanim's Shard can be used to easily kill many of Terrorblade's illusions, it can also hex the real Terrorblade, silencing him, disarming him, slowing him, and muting him.
* 
Bad Juju can weaken Terrorblade's armor every time Dazzle casts a spell while strengthening armor of Dazzle's allies.
Additional:
* Aghanim's Shard upgraded Poison Touch can be used to easily kill many of Terrorblade's illusions from both 
Conjure Image and 
Manta Style, it can also hex the real Terrorblade, silencing him, disarming him, slowing him, muting him and rendering him unable to do anything at all.
* Shallow Grave can be used to save an ally whom Terrorblade has used Sunder on under the condition Dazzle is quick enough to do it. And since Terrorblade has no "real" burst damage potential outside from Sunder, Dazzle will usually have plenty of time to save an allied hero on which Sunder was used.
* Shadow Wave will always damage Terrorblade and his illusions whenever Terrorblade has no 
Metamorphosis available to use, while healing Dazzle's allies.
* Bad Juju can weaken Terrorblade's armor every time Dazzle casts a spell while strengthening armor of Dazzle's allies.
Keeper of the Light
* Keeper of the Light can stall pushes with Illuminate. This makes him strong against pushing heroes: Terrorblade Naga siren Nature's Prophet and Anti-Mage
Dazzle
* Shallow Grave can prevent the death of an ally that is trapped inside the Chronosphere.
* Shadow Wave lets Dazzle heal allies and damage enemies from outside Chronosphere.
Keeper of the Light
* Any hero that can nullify effects of Chronosphere: (Keeper of the Light with Aghanim's Scepter during daytime, Winter Wyvern), banishing him or Faceless Void (
Outworld Destroyer, Shadow Demon, 
Earth Spirit with Aghanim's Scepter) or protecting him in other ways (Dazzle, Oracle, Abaddon) can greatly limit Chronosphere's potential.
Dazzle
* Poison Touch severely slows down Chen, deals damage over time and weakens his armor every time he gets attacked by Dazzle or any of his allies. Aghanim's Shard upgraded Poison Touch can hex Chen and prevent him from saving his allies with 
Hand of God.
* Neither Chen nor his converted creeps have burst damage at all, so Dazzle will always have plenty of time to save his allies with Shallow Grave.
* Dazzle can use Shadow Wave can heal his allies, kill Chen's creeps and damage Chen himself.
* Bad Juju can weaken Chen's armor, and the armor of his creeps every time Dazzle casts a spell while strengthening armor of Dazzle's allies.
Keeper of the Light
* Heroes with summons/illusions/neutral creep armies: 
Beastmaster, Chen, Naga Siren
Dazzle
* Heroes that can slow Charge of Darkness by a huge amount: 
Venomancer, 
Viper, Dazzle, 
Arc Warden, Lion.
Keeper of the Light
* Heroes that punish mobile heroes: Bloodseeker, Keeper of the Light.
Keeper of the Light
* Blinding Light can knock Monkey King outside of his ultimate, Wukong's Command and can blind him.
* Will-O-Wisp will stun Monkey King from Tree Dance by destroying his tree.
Additional:
* 
Blinding Light can easily push Monkey King out of Wukong's Command, as well as blinding him.
* Monkey King is vulnerable to burst damage, 
Solar Bind makes him more so
* However, Keeper of the Light can be easily ganked by Monkey King during early-mid game stage.
Keeper of the Light
* Illuminate clears Beastmaster's summons and is effective against his push.
Dazzle
* 
Reaper's Scythe is very predictable and gives Dazzle plenty of time to react with Shallow Grave: Dazzle just has to keep a close eye on his allies below 50% health.
* However, Dazzle must be sure to use Shadow Wave on that ally immediately after, or they will die from 
Heartstopper Aura when the Shallow Grave ends!
Additional:
* Dazzle's Shadow Wave is a spammable healing ability that spreads around his entire team, slowing the death of his teammates as effectively as Necrophos spreads damage to them.
* If not immediately, Shallow Grave delays his ally from gradually dying to Necrophos's abilities, especially Reaper's Scythe.
* However, bear in mind that Dazzle's Poison Touch, Shadow Wave and Bad Juju all deal physical damage, and Dazzle has no abilities to help him deal magical damage at all, which can cause problems for Dazzle to kill Necrophos if he uses Ghost Shroud to protect himself.
Dazzle
* Venomancer's damage-over-time abilities are easier to heal through with numerous Shadow Waves than other types of damage, and it's simple to time a Shallow Grave until the last possible second to save a teammate from them.
Dazzle
* Shadow Wave provides good sustain against Tinker's spammable abilities.
* Shallow Grave can stop Tinker from bursting down a target.
Dazzle
* Heroes that can save their allies can be a big problem for Mars: Dazzle, Omniknight.
Keeper of the Light
* Heroes with extremely slow movement speed will cripple against Solar Bind: Medusa, Viper
Additional:
* 
Will-O-Wisp will keep Medusa busy after she got hit by Blinding Light.
Keeper of the Light
* Any hero who can counter-initiate in anticipation without getting caught in Reverse Polarity: 
Sven, Omniknight, Enigma, 
Luna, Naga Siren, 
Mars, 
Jakiro, Venomancer, 
Elder Titan, 
Faceless Void, 
Rubick, Keeper of the Light, 
Pugna, Invoker, 
Spectre, 
Alchemist, 
Treant Protector, Lina, Oracle, Zeus, Shadow Shaman, 
Phoenix, 
Razor, 
Huskar, 
Batrider, 
Kunkka, 
Tidehunter, Wraith King, 
Sand King, Medusa, 
Dawnbreaker.
Keeper of the Light
* Certain heroes can mess up with Pangolier's positioning and timing (especially if he intends to use Rolling Thunder during combat): 
Vengeful Spirit, Keeper of the Light, Huskar, Dark Seer
Keeper of the Light
* Heroes with dispels: Legion Commander, Oracle, Slark, Phantom Lancer
Dazzle
* Heroes that can deny Slark early kills will prevent him from snowballing: Dazzle, Abaddon.
Keeper of the Light
* Melee carries during the laning phase: Sven, Slark
Keeper of the Light
* 
Press the Attack can dispel Blinding Light or Solar Bind from a hero.
* 
Duel can be used to instantly take Keeper of the Light out of a team-fight.
Dazzle
* Shallow Grave prevents Legion Commander from killing her opponents in Duels.
* Shadow Wave will heal an ally caught in a Duel, as well as dealing damage to Legion Commander.
Keeper of the Light
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: Arc Warden, Keeper of the Light, Riki, 
Tinker
Keeper of the Light
* Heroes with extremely slow movement speed will cripple against Solar Bind: Medusa, Viper
Keeper of the Light
* Melee carries during the laning phase: Sven, Slark
Keeper of the Light
* Heroes which rely exclusively on right clicks will struggle somewhat against Blinding Light: Phantom Assassin, Wraith King, Medusa
Dazzle
* 
Mirror Image's illusions can easily walk straight at Dazzle and attack him, due to Dazzle's lack of reliable AoE nukes or disables.
* 
Ensnare roots Dazzle or his allies, making it harder to stay in range of Dazzle's saving abilities.
* 
Song of the Siren can be used to initiate a fight with superior positioning, potentially zoning Dazzle's high-impact spells out of the fight.
Dazzle
* Dazzle can instantly destroy all of Naga Siren's illusions from Mirror Image with Aghanim's Shard upgraded Poison Touch used on her or any of her illusions.
Keeper of the Light
* Keeper of the Light can stall pushes with Illuminate. This makes him strong against pushing heroes: Terrorblade Naga siren Nature's Prophet and Anti-Mage
Dazzle
* Once he buys Aghanim's Shard, Dazzle's Poison Touch can hex enemies, and hex can instantly kill illusions, making Dazzle strong against heroes who rely on illusions. Bear in mind that 
Chaos Knight is the exception because his 
Phantasms are strong illusions that are immune to abilities that can instantly kill illusions.
Keeper of the Light
* Keeper of the Light can stall pushes with Illuminate. This makes him strong against pushing heroes: Terrorblade Naga siren Nature's Prophet and Anti-Mage
Dazzle
* Heroes with armor reducing abilities greatly hinder Visage's defense like 
Slardar and Dazzle.
Keeper of the Light
* Heroes with channeling abilities: Enigma, Witch Doctor, Crystal Maiden.
Keeper of the Light
* Illuminate can wipe the pushing Eidolons in a lane with ease, diminishing Enigma's laning presence by a lot.
* Solar Bind will severely slow down Enigma and make him more vulnerable to magical damage more he moves for it's duration.
* However, Keeper of the Light does not have any way to cancel Black Hole outside from Will-O-Wisp from Aghanim's Scepter.
Dazzle
* Some heroes with extreme range, like Zeus, Invoker or Clockwerk, can snipe your allies from anywhere after your Grave has expired.
Dazzle
* Aghanim's Shard upgraded Poison Touch can be used to hex Clockwerk, silencing him, disarming him, slowing him, and muting him, and thus rendering him unable to use 
Blade Mail to return damage or to do anything at all.
* Shadow Wave will hit Clockwerk every time when he's fighting with an enemy inside Power Cogs.
* Due to Clockwerk's very low damage output, Dazzle will have more than enough time to Shallow Grave any enemy hero Clockwerk initiates on.
Additional:
* Shadow Wave will hit Clockwerk every time when he's fighting with an enemy inside 
Power Cogs.
* Due to Clockwerk's steady damage output, Dazzle has plenty of time to Shallow Grave anyone Clockwerk initiates on.
Dazzle
* Support heroes with low mobility can be slowed further by Incapacitating Bite, and swarmed by Spiderlings for an easy kill: Shadow Shaman, 
Visage, Dazzle, Rubick, 
Lich.
Keeper of the Light
* Illuminate wipes out Broodmother's spiders and prevents her from pushing the lane. It also gives vision to reveal where broodmother is hiding in the trees.
Keeper of the Light
* Juggernaut's 
Healing Ward keeps his team healthy even when pushing against Keeper of the Light's Illuminate.
* Blade Fury can dispel Blinding Light, as well as dodge an incoming Illuminate. Juggernaut can attack towers during Blade Fury, so he can dodge an Illuminate without having to stop pushing.
* Should Keeper of the Light obtain Will-o-Wisp through purchasing an Aghanim's Scepter, Juggernaut can make quick work of Ignis Fatuus without being interrupted by its pull.
* Keeper of the Light has low health, low armor, and no natural defense against 
Blade Fury.
Additional:
* Blade Fury allows him to be immune to all of Ezalor's abilities.
* Healing Ward heals his entire team, mitigating Ezalor's weak magical burst damage.
Dazzle
* Heroes with abilities that can save teammates are also effective such as Shadow Demon, Dazzle, Oracle, 
Bane, Pugna, 
Tusk, Winter Wyvern, Io, 
Underlord, Treant Protector and Keeper of the Light.
Keeper of the Light
* Keeper of the Light's Blinding Light makes Juggernaut miss his attacks. However, it can be dispelled easily with Blade Fury.
Keeper of the Light
* Any hero who lanes very poorly will struggle with Primal Beast's potential snowball in the very early levels, like Keeper of the Light, Luna, Templar Assassin...
Dazzle
* Primal Beast really suffers against supports he cannot bully in the lane: this includes Dazzle, Shadow Demon and 
Dark Willow since they can use their respective abilities to stop Primal Beast from dealing burst damage, or make it hard for him to stay in range.
Keeper of the Light
* With 
Bloodthorn, Clinkz becomes a strong counter to heroes who rely on evasion and blind such as Windranger, Phantom Assassin, Troll Warlord and Keeper of the Light.
Dazzle
* Heroes that excel at grouping up with their team very early will be able to take advantage of a Clinkz that tries to pick off heroes that are alone: 
Brewmaster, Dazzle, Tidehunter.
Keeper of the Light
* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, 
Silencer, Keeper of the Light, Venomancer, etc.
Dazzle
* Heroes with abilities that reduce armor will make Huskar very vulnerable: 
Weaver, Dazzle, 
Bristleback, Vengeful Spirit.
Keeper of the Light
* Heroes with hastes: Dark Seer, Lycan
Keeper of the Light
* Keeper of the Light has a blind, which causes Lycan to miss his attacks.
Dazzle
* A well-timed
Global Silence prevents Dazzle from saving allies with Shallow Grave or Shadow Wave. Items that could dispel the silence are expensive, and difficult for Dazzle to farm from a support role.
Arcane Curse and 
Last Word cause long damage over time, which may outlast Shallow Grave.
*
Keeper of the Light
* Being a cast-oriented hero, Ezalor will suffer from all of Silencer's abilities.
Global Silence is a guaranteed lengthy silence which will render Ezalor useless in a teamfight.
Arcane Curse and 
Last Word are good against any caster, since they are extremely potent.
*
*
* However, it should be worth mentioning that a smart Ezalor will buy Eul's Scepter of Divinity to dispel Silencer's abilities. Combined with the level 20 talent (Chakra Magic applies a basic dispel), Ezalor can purge Silencer's abilities off allies and himself alike.