River Song

surveil — 93 cards in River Song's colors can cause this.

1. Diviner of Victory // Unwind History — When Diviner of Victory // Unwind History surveils, River Song puts a +1/+1 counter on itself

92 other cards cause it too. These are the ones with the most connections.

scry — 229 cards in River Song's colors can cause this.

1. Zaffai, Thunder Conductor — When Zaffai, Thunder Conductor scries, River Song puts a +1/+1 counter on itself
2. Eager Construct — When Eager Construct scries, River Song puts a +1/+1 counter on itself
3. Myr Custodian — When a permanent scries thanks to Myr Custodian, River Song puts a +1/+1 counter on itself
4. Kozilek's Command — When Kozilek's Command scries, River Song puts a +1/+1 counter on itself
5. Ingenious Mastery — When Ingenious Mastery scries, River Song puts a +1/+1 counter on itself
6. Model of Unity — When Model of Unity scries, River Song puts a +1/+1 counter on itself

223 other cards cause it too. These are the ones with the most connections.

a Rogue creature enters the battlefield — 276 cards in River Song's colors can cause this (River Song is one).

1. Cloak and Dagger — When River Song enters, Cloak and Dagger triggers

search your library — 286 cards in River Song's colors can cause this.

1. Jace, Architect of Thought — When a creature, artifact, enchantment, instant, sorcery, planeswalker or battle searches a library thanks to Jace, Architect of Thought, River Song puts a +1/+1 counter on itself
2. Arcum Dagsson — When an artifact searches a library thanks to Arcum Dagsson, River Song puts a +1/+1 counter on itself
3. Krenko's Buzzcrusher — When a land searches a library thanks to Krenko's Buzzcrusher, River Song puts a +1/+1 counter on itself
4. Magmatic Hellkite — When a land searches a library thanks to Magmatic Hellkite, River Song puts a +1/+1 counter on itself
5. Sandworm — When a land searches a library thanks to Sandworm, River Song puts a +1/+1 counter on itself
6. Grinning Totem — When a permanent searches a library thanks to Grinning Totem, River Song puts a +1/+1 counter on itself
7. Jester's Cap — When a permanent searches a library thanks to Jester's Cap, River Song puts a +1/+1 counter on itself
8. Jester's Mask — When a permanent searches a library thanks to Jester's Mask, River Song puts a +1/+1 counter on itself
9. Price of Freedom — When a land searches a library thanks to Price of Freedom, River Song puts a +1/+1 counter on itself
10. Sundering Eruption // Volcanic Fissure — When a land searches a library thanks to Sundering Eruption // Volcanic Fissure, River Song puts a +1/+1 counter on itself

276 other cards cause it too. These are the ones with the most connections.

a creature gets a counter — 647 cards in River Song's colors can cause this (River Song is one).

When River Song gets a counter:

1. Casey Jones, Back Alley Brute — deals that much damage
2. Danny Pink — draws you 1 card
3. Omarthis, Ghostfire Initiate — puts a counter on a permanent
4. Rikku, Resourceful Guardian — triggers

1 other card cares about it too. These are the ones with the most connections.

anything deals noncombat damage — 1,963 cards in River Song's colors can cause this (River Song is one).

When River Song deals noncombat damage:

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

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

life is lost — 1,408 cards in River Song's colors can cause this (River Song is one).

When River Song makes a player lose life:

1. Aether Syphon — raises your speed
2. Vnwxt, Verbose Host — raises your speed
3. Slick Imitator — raises your speed
4. Howlsquad Heavy — raises your speed
5. Walking Sarcophagus — raises your speed
6. Starting Column — raises your speed
7. Racers' Scoreboard — raises your speed
8. Outpace Oblivion — raises your speed
9. Kickoff Celebrations — raises your speed
10. Goblin Surveyor — raises your speed

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

a card is drawn — 1,924 cards in River Song's colors can cause this (River Song is one).

When River Song makes a player draw a card:

1. Niv-Mizzet, Parun — deals 1 damage
2. The Locust God — makes a token
3. Diviner's Wand — gets +1/+1
4. Ominous Seas — puts a foreshadow counter on itself
5. Iron Man, Armored Avenger — puts a counter on a creature
6. Psychosis Crawler — makes each opponent lose 1 life
7. Lyla, Holographic Assistant — puts a counter on a creature
8. Data, New Life — puts a +1/+1 counter on itself
9. Chasm Skulker — puts a +1/+1 counter on itself
10. Nadir Kraken — puts a +1/+1 counter on itself

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

anything gets a counter — 1,298 cards in River Song's colors can cause this (River Song is one).

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

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

a Human enters the battlefield — 1,353 cards in River Song's colors can cause this (River Song is one).

When River Song enters:

1. Captain of the Mists — untaps itself
2. Erkenbrand, Lord of Westfold — gives +1/+0
3. Vigilante Justice — deals 1 damage

a creature attacks — 6,189 cards in River Song's colors can cause this (River Song is one).

When River Song attacks:

1. Adaptive Omnitool — searches a library
2. Kindred Discovery — draws you 1 card
3. Saw — sacrifices a creature
4. Ultima Weapon — kills a creature an opponent controls
5. Total War — kills a creature
6. The Spear of Leonidas — triggers

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

a creature blocks — 6,189 cards in River Song's colors can cause this (River Song is one).

When River Song blocks:

1. Tide of War — sacrifices a creature
2. Dead-Iron Sledge — kills a creature
3. Dwindle — kills a creature

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

anything attacks — 6,189 cards in River Song's colors can cause this (River Song is one).

When River Song attacks:

1. ED-E, Lonesome Eyebot — puts a quest counter on itself
2. Madame Web, Clairvoyant — mills a card
3. Shaun, Father of Synths — makes a token
4. Gossip's Talent — triggers
5. Inti, Seneschal of the Sun — triggers
6. Gut, True Soul Zealot — sacrifices a creature or artifact
7. Cool but Rude — draws and discards
8. Swashbuckler Extraordinaire — sacrifices a Treasure

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

a creature enters the battlefield — 6,749 cards in River Song's colors can cause this (River Song is one).

When River Song enters:

1. Slash, Reptile Rampager — deals 2 damage
2. Gimli of the Glittering Caves — puts counters on a permanent
3. Ray Fillet, Wave Warrior — puts a counter on itself
4. Wingnut, Bat on the Belfry — grants flying, haste and menace
5. Raphael, Most Attitude — exiles a card from your library

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