Python

a Snake deals combat damage — 226 cards in the game can cause this (Python is one).

1. Seshiro the Anointed — When Python deals combat damage, Seshiro the Anointed draws you 1 card

a nontoken Snake enters the battlefield — 227 cards in the game can cause this (Python is one).

1. Sosuke's Summons — When Python enters, Sosuke's Summons returns itself from the graveyard

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

1. Far Fortune, End Boss — When Python attacks, Far Fortune, End Boss deals 1 damage
2. Temmet, Naktamun's Will — When Python attacks, Temmet, Naktamun's Will draws you 1 card
3. Grim Javelineer — When Python attacks, Grim Javelineer gives +1/+0
4. Invisible Woman — When Python attacks, Invisible Woman triggers
5. Caesar, Legion's Emperor — When Python attacks, Caesar, Legion's Emperor sacrifices a creature
6. Guide of Souls — When Python attacks, Guide of Souls triggers
7. Campsite Cuisine — When Python attacks, Campsite Cuisine sacrifices a Food
8. Gossip's Talent — When Python attacks, Gossip's Talent triggers
9. Banon, the Returners' Leader — When Python attacks, Banon, the Returners' Leader draws and discards
10. Toph, Earthbending Master — When Python attacks, Toph, Earthbending Master puts a counter on a permanent

112 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 (Python is one).

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

180 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 (Python is one).

1. Mage Hunters' Onslaught — When Python blocks, Mage Hunters' Onslaught makes a player lose 1 life
2. Carnage Gladiator — When Python blocks, Carnage Gladiator makes a player lose 1 life
3. Barrow-Blade — When Python blocks, Barrow-Blade strips abilities
4. Heat of Battle — When Python blocks, Heat of Battle deals 1 damage
5. Battle Strain — When Python blocks, Battle Strain deals 1 damage
6. Favor of the Woods — When Python blocks, Favor of the Woods gains you 3 life
7. Tide of War — When Python blocks, Tide of War sacrifices a creature
8. Dead-Iron Sledge — When Python blocks, Dead-Iron Sledge kills a creature
9. Dwindle — When Python blocks, Dwindle kills a creature
10. Shield of the Righteous — When Python blocks, Shield of the Righteous triggers

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

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

1. Mardu Ascendancy — When Python attacks, Mardu Ascendancy makes a token
2. Basri Ket — When Python attacks, Basri Ket makes a token
3. Militia's Pride — When Python attacks, Militia's Pride makes a token

a creature deals combat damage — 17,934 cards in the game can cause this (Python is one).

When Python deals combat damage:

1. Locutus of Borg — makes a token
2. Antagonist Incorporator — makes a token
3. Hive Mind Coprocessor — makes you lose life

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

a creature is cast — 18,010 cards in the game can cause this (Python is one).

1. Primeval Bounty — When Python is cast, Primeval Bounty makes a token
2. Bloodbond March — When Python is cast, Bloodbond March brings a card back
3. Dancing from Dark to Dawn — When Python is cast, Dancing from Dark to Dawn puts that spell's mana value counters on a creature
4. Endrek Sahr, Master Breeder — When Python is cast, Endrek Sahr, Master Breeder makes that spell's mana value tokens
5. Summon: Fenrir — When Python is cast, it arrives with counters thanks to Summon: Fenrir
6. Summon: Brynhildr — When Python is cast, Summon: Brynhildr grants haste
7. Skittering Horror — When Python is cast, Skittering Horror sacrifices itself
8. Skittering Skirge — When Python is cast, Skittering Skirge sacrifices itself
9. Skittering Monstrosity — When Python is cast, Skittering Monstrosity sacrifices itself
10. Silverback Elder — When Python is cast, Silverback Elder triggers

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

a nontoken creature enters the battlefield — 18,448 cards in the game can cause this (Python is one).

1. Riku of Two Reflections — When Python enters, Riku of Two Reflections makes a token
2. Samwise Gamgee — When Python enters, Samwise Gamgee makes a token
3. Dual Nature — When Python enters, Dual Nature makes a token
4. Angelic Sell-Sword — When Python enters, Angelic Sell-Sword makes a token
5. Lonis, Cryptozoologist — When Python enters, Lonis, Cryptozoologist triggers

28 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 (Python is one).

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

299 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 (Python is one).

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

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