Brightmare

a creature becomes tapped — 565 cards in the game can cause this (Brightmare is one).

When Brightmare becomes tapped:

1. Unctus, Grand Metatect — draws you 1 card
2. Sharae of Numbing Depths — draws you 1 card
3. Rewrite History — draws you 1 card
4. Stinging Licid — deals 2 damage
5. Gideon's Avenger — puts a +1/+1 counter on itself
6. Icewrought Sentry — gets +2/+1
7. Hawkeye's Bow — deals 1 damage
8. Cryoshatter — kills a creature
9. Don't Move — kills a creature
10. Hylda of the Icy Crown — triggers

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

life is gained — 2,076 cards in the game can cause this (Brightmare is one).

When Brightmare gains life:

1. Dina, Soul Steeper — makes each opponent lose 1 life
2. Marina Vendrell's Grimoire — draws you that many cards
3. South Wind Avatar — makes each opponent lose 1 life
4. Rodolf Duskbringer — grants indestructible
5. Fiendish Panda — puts a +1/+1 counter on itself
6. Veinwitch Coven — brings a card back
7. Cleric Class — puts a counter on a creature
8. Lich's Mastery — draws you that many cards
9. Wall of Limbs — puts a +1/+1 counter on itself
10. Ratchet, Field Medic // Ratchet, Rescue Racer — triggers

84 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 (Brightmare is one).

When Brightmare attacks:

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

116 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 (Brightmare is one).

When Brightmare attacks:

1. Adaptive Omnitool — searches a library
2. Anthem of Rakdos — gives +2/+0
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. Anim Pakal, Thousandth Moon — puts a +1/+1 counter on itself
7. Saw — sacrifices a creature
8. Gisa's Favorite Shovel — makes an opponent sacrifice a creature
9. Ultima Weapon — kills a creature an opponent controls
10. Total War — kills a creature

181 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 (Brightmare is one).

When Brightmare blocks:

1. Mage Hunters' Onslaught — makes a player lose 1 life
2. Carnage Gladiator — makes a player lose 1 life
3. Barrow-Blade — strips abilities
4. Tide of War — sacrifices a creature
5. Dead-Iron Sledge — kills a creature
6. Dwindle — kills a creature
7. Shield of the Righteous — triggers

21 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 (Brightmare is one).

When Brightmare attacks:

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

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

When Brightmare enters:

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

301 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 (Brightmare is one).

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

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