Apocalypse Hydra

a creature gets a counter — 2,691 cards in the game can cause this (Apocalypse Hydra is one).

When Apocalypse Hydra gets a counter:

1. Hollowmurk Siege — draws you 1 card
2. Ant-Man, Colony Commander — makes a token
3. Earth Kingdom General — gains you that much life
4. Casey Jones, Back Alley Brute — deals that much damage
5. Generous Patron — draws you 1 card
6. Shalai and Hallar — deals that much damage
7. Danny Pink — draws you 1 card
8. Enduring Scalelord — puts a +1/+1 counter on itself
9. Bold Plagiarist — puts counters on a permanent
10. Mikey & Leo, Chaos & Order — draws you 1 card

33 other cards care about it too. These are the ones with the most connections.

anything deals noncombat damage — 3,068 cards in the game can cause this (Apocalypse Hydra is one).

When Apocalypse Hydra deals noncombat damage:

1. Quest for Pure Flame — puts a quest counter on itself
2. Soul-Scar Mage — puts that many counters on a permanent
3. Fear of Burning Alive — deals that amount damage
4. Niv-Mizzet, Visionary — draws you that many cards
5. Ghyrson Starn, Kelermorph — deals 2 damage
6. Chandra's Incinerator — deals that much damage
7. Chandra's Pyreling — gets +1/+0
8. Talon of Pain — puts a charge counter on itself
9. Thor, Guardian of Midgard — exiles a card from your library
10. Virtue of Courage // Embereth Blaze — exiles a card from your library

36 other cards care about it too. These are the ones with the most connections.

life is lost — 3,160 cards in the game can cause this (Apocalypse Hydra is one).

When Apocalypse Hydra makes a player lose life:

1. Far Fortune, End Boss — raises your speed
2. Zahur, Glory's Past — raises your speed
3. Mendicant Core, Guidelight — raises your speed
4. Aether Syphon — raises your speed
5. Vnwxt, Verbose Host — raises your speed
6. Embalmed Ascendant — raises your speed
7. Slick Imitator — raises your speed
8. Oath of Lim-Dûl — sacrifices an enchantment
9. Marina Vendrell's Grimoire — triggers
10. Lich's Mastery — triggers

46 other cards care about it too. These are the ones with the most connections.

anything gets a counter — 4,415 cards in the game can cause this (Apocalypse Hydra is one).

1. All Will Be One — When Apocalypse Hydra gets a counter, All Will Be One deals that much damage

8 other cards care about it too. These are the ones with the most connections.

a creature attacks — 17,934 cards in the game can cause this (Apocalypse Hydra is one).

When Apocalypse Hydra attacks:

1. Anthem of Rakdos — gives +2/+0
2. Adaptive Omnitool — searches a library
3. Kindred Discovery — draws you 1 card
4. Invasion of New Capenna // Holy Frazzle-Cannon — puts counters on a permanent
5. Chorale of the Void — brings a card back
6. Saw — sacrifices a creature
7. Gisa's Favorite Shovel — makes an opponent sacrifice a creature
8. Ultima Weapon — kills a creature an opponent controls
9. Total War — kills a creature

181 other cards care about it too. These are the ones with the most connections.

anything attacks — 17,934 cards in the game can cause this (Apocalypse Hydra is one).

When Apocalypse Hydra attacks:

1. Temmet, Naktamun's Will — draws you 1 card
2. Grim Javelineer — gives +1/+0
3. Invisible Woman — triggers
4. Caesar, Legion's Emperor — sacrifices a creature
5. Guide of Souls — triggers
6. Campsite Cuisine — sacrifices a Food
7. Gossip's Talent — triggers
8. Banon, the Returners' Leader — draws and discards
9. Toph, Earthbending Master — puts a counter on a permanent
10. Three Dog, Galaxy News DJ — sacrifices an Aura

113 other cards care about it too. These are the ones with the most connections.

a creature blocks — 17,934 cards in the game can cause this (Apocalypse Hydra is one).

When Apocalypse Hydra blocks:

1. Mage Hunters' Onslaught — makes a player lose 1 life
2. Tide of War — sacrifices a creature
3. Dead-Iron Sledge — kills a creature
4. Dwindle — kills a creature

24 other cards care about it too. These are the ones with the most connections.

a creature enters the battlefield — 19,800 cards in the game can cause this (Apocalypse Hydra is one).

When Apocalypse Hydra enters:

1. Slash, Reptile Rampager — deals 2 damage
2. The Neutrinos — gets +1/+0
3. Wingnut, Bat on the Belfry — grants flying, haste and menace
4. Aetherstorm Roc — puts a counter on a permanent you control
5. Raphael, Most Attitude — exiles a card from your library

306 other cards care about it too. These are the ones with the most connections.

anything enters the battlefield — 26,499 cards in the game can cause this (Apocalypse Hydra is one).

1. Prowl, Stoic Strategist // Prowl, Pursuit Vehicle — When Apocalypse Hydra enters, Prowl, Stoic Strategist // Prowl, Pursuit Vehicle puts a +1/+1 counter on itself

43 other cards care about it too. These are the ones with the most connections.