Medusa/Counters

Bad against...

 * Anti-Mage's burns Medusa's mana easily, especially when coupled with a.
 * Can easily initiate on Medusa with, burning her mana or forcing her to use Stone Gaze.
 * is effective against Medusa's big mana pool and mana usage, presenting a huge hazard to Medusa's allies around her since her Mana Shield still gives her some protection if she has mana.


 * Phantom Lancer with will very quickly burn Medusa's mana, making Mana Shield significantly less effective.
 * 's 1 second invulnerability can be used to dodge Medusa's petrification from Stone Gaze, as well as Mystic Snake.
 * Phantom Lancer's illusions outnumber Medusa's targets from Split Shot, likely shielding your team in the process.


 * Level 4 burns 38,5% of Medusa's mana every 4 seconds if Medusa only increases her mana pool with intelligence. Additionally, 60% of the  damage gets mitigated by Mana Shield, burning even more mana.
 * Mystic Snake and Split Shot is uncontrollable damage, possibly proccing . However, they do not target an invisible Nyx.
 * Medusa lacks single target damage, making Nyx with extremely hard to deal with if Medusa is your main damage.


 * and reduces Medusa's mana.
 * will not interrupt and will petrify you if you're facing towards Medusa's ( usually OD himself while trying to cast it and after ) direction before she was banished, but it will stop her from getting a good position


 * is a large mana burn nuke which can hit Medusa's Mana shield with enough damage to lose even more mana.
 * disarms medusa's ability to deal pseudo-AOE damage during teamfights.
 * allows the opposing team to repeatedly stun Medusa in short succession, preventing her from successfully casting her ultimate due to its long cast time.


 * Medusa is especially vulnerable to Essence Shift, as both Strength and Intelligence contribute to her effective HP.


 * Sniper can outrange both Medusa's arrows and Stone gaze, allowing him to lock her down during a teamfight.

Others

 * Heroes with mana burning abilities will make Medusa much less tanky:, , , ,
 * Heroes that build will also make Medusa much less tanky: ,

Items

 * burns away the mana Medusa needs for Mana Shield.
 * provides mana burning summons, and Medusa is especially vulnerable to getting hit with Last Will.
 * disarms Medusa's Split shot effectively.

Good against...

 * Medusa's Split shot allows her to focus on killing the tombstone while still dealing damage to the enemy heroes, or simply ignore the tombstone and allow her split shot to prevent the zombies from building up.


 * Mana shield effectively counters Reaper's Scythe, as it can tank 60% of the damage. With sufficient mana, Medusa can survive the Scythe at 19%/22%/24%, and Agh's only raises the killing threshhold to 28%.
 * Heartstopper Aura does not chip away at Medusa's mana.
 * Necrophos has a movement speed equal to Medusa, and is easy to chase down with a slowing item in Medusa's inventory.


 * Enchantress often has a small army of neutral creeps, allowing Medusa to hit her with a later bounce of her Mystic Snake.
 * Enchantress passive Untouchable is easily avoided by Medusa. Simply target another enemy hero or creep, and let split shot hit her.


 * Medusa is one of Sven's primal counter since he relies on man-fighting which is prevented and kited with stone gaze
 * Also has a small mana pool and mystic snake does pure damage while a unit is petrified, a minor buff that is useful in case he used warcry
 * A farmed Medusa will be a very hard kill for Sven forcing him to go on others while she chips away at him, usually building Eye of Skadi will leave Sven very slow and soon dead


 * Completely negates the burst damage from the shotgun build as mana shield blocks all damage before reductions


 * Another example, mana shield negates all damage before reductions meaning that Amplify Damage won't do much unless Medusa is completely out of mana


 * A very immobile hero very likely to Sven, making Medusa hard to catch or even use your Open Wounds on her as a Medusa will almost always go Linkens Sphere, making Lifestealer an easy target for Stone Gaze

Others

 * Heroes that rely on illusions to deal damage will find their illusions destroyed by Stone Gaze and Split Shot: ,
 * Heroes that rely on summons. A few strong summons, such as with Lycan or allow Medusa to bounce her Mystic Snake between them to hit the hero for additional damage. Many weak summons, such as Broodmother or Lycan, force the group to tank Medusa's split shot.
 * Heroes that rely on BKB to survive teamfights.
 * In theory Medusa counters all Melee heroes, even though that is not the case with Mana-burning heroes and heroes with escapes, Medusa can outfight even AM if he gets petrified so by all means Medusa should be feared

Works well with...

 * Deals area damage with ultimate and can stun/disable to cast Stone Gaze and make it easier to freeze enemy heroes.


 * Berserker's Call can force enemies to face Medusa during her Stone Gaze.


 * amplifies Medusa's Split Shot.
 * Drow Ranger's midgame strength allows Medusa to farm safely, then take the lead once Drow Ranger's relative strength drops in the late game.


 * During teamfights, casting Disruption upon Medusa creates a pair of illusions with Split Shot and 75% of her base damage.
 * Shadow Demon can stack 2-3 jungle camps at the same time, speeding up Medusa's farming phase.
 * Stoned enemies are immune to magical damage, but Shadow Poison can still build stacks during the Stoned phase.


 * Witch Doctor's ultimate deals physical damage, so if Medusa managed to petrify a bunch of enemies with the given physical damage bonus, Death Ward can shred through enemies especially with Aghanim Scepter

Others

 * Heroes that deal pure damage like Tinker's Aghanim Laser upgrade can give him enough time to cast it a couple of times or Outworld Devourer can deal the full damage of his Arcane Orb and stack a lot of intelligence for those 3 seconds of Stone Gaze
 * Everyone with good physical damage and lock down for a good Stone Gaze
 * Abilities that grant sustain or heroes with sustain to keep the enemy kited and distracted while Medusa slowly destroys them

List of heroes that counter Medusa, and list of heroes that work well with Medusa.