Agna Qel'a

a land enters the battlefield — 1,560 cards in the game can cause this (Agna Qel'a is one).

When Agna Qel'a enters:

1. Primeval Bounty — gains you 3 life
2. Toph, Earthbending Master — puts a counter on a permanent
3. Dancing from Dark to Dawn — makes a token
4. Emeria Shepherd — brings a card back
5. Quest for the Necropolis — puts a quest counter on itself
6. Soul Stair Expedition — puts a quest counter on itself
7. Nissa of Shadowed Boughs — puts counters on a permanent
8. Thranduil, Sindarin Liege // Silvan Rally — makes a token
9. Silvan Reveler — returns itself from the graveyard
10. Floral Evoker — puts a +1/+1 counter on itself

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

a card is discarded — 2,042 cards in the game can cause this (Agna Qel'a is one).

When Agna Qel'a makes a player discard a card:

1. Ivora, Insatiable Heir — puts a +1/+1 counter on itself
2. Cool but Rude — deals 2 damage
3. Containment Construct — brings a card back
4. Moonstone, Harsh Mistress — brings a card back
5. Lazotep Chancellor — puts 2 counters on a Zombie or Army
6. Magmakin Artillerist — deals that much damage
7. Inti, Seneschal of the Sun — exiles a card from your library
8. Pitchstone Wall — sacrifices itself
9. Currency Converter — exiles it
10. Hostile Investigator — triggers

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

a card is drawn — 3,815 cards in the game can cause this (Agna Qel'a is one).

When Agna Qel'a makes a player draw a card:

1. Temmet, Naktamun's Will — gives +1/+1
2. Niv-Mizzet, Parun — deals 1 damage
3. Aether Syphon — mills a card
4. The Locust God — makes a token
5. Starving Revenant — makes each opponent lose 1 life
6. Diviner's Wand — gets +1/+1
7. Ominous Seas — puts a foreshadow counter on itself
8. Dream Trawler — gets +1/+0
9. Iron Man, Armored Avenger — puts a counter on a creature
10. The Astonishing Ant-Man — puts a +1/+1 counter on itself

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

a card in a graveyard — 7,589 cards in the game can cause this (Agna Qel'a is one).

1. Samwise Gamgee — Agna Qel'a puts cards into the graveyard that Samwise Gamgee can bring back
2. Bloodbond March — Agna Qel'a puts cards into the graveyard that Bloodbond March can bring back
3. Thor, God of Thunder — Agna Qel'a puts cards into the graveyard that Thor, God of Thunder can bring back
4. Gale, Waterdeep Prodigy — Agna Qel'a puts cards into the graveyard that Gale, Waterdeep Prodigy can bring back
5. Harness the Storm — Agna Qel'a puts cards into the graveyard that Harness the Storm can bring back
6. Transplant Theorist — Agna Qel'a puts cards into the graveyard that Transplant Theorist can bring back
7. Heart-Shaped Herb — Agna Qel'a puts cards into the graveyard that Heart-Shaped Herb can bring back
8. Wayward Angel — Agna Qel'a fills your graveyard toward the 7 or more cards Wayward Angel needs
9. Rescue from the Underworld — Agna Qel'a puts cards into the graveyard that Rescue from the Underworld can bring back
10. Victimize — Agna Qel'a puts cards into the graveyard that Victimize can bring back

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

anything goes to a graveyard — 7,589 cards in the game can cause this (Agna Qel'a is one).

When a card hits the graveyard thanks to Agna Qel'a:

1. Quest for Ancient Secrets — puts a quest counter on itself
2. Planar Void — hits a graveyard
3. Measure of Wickedness — gives an opponent control of itself
4. Energy Field — sacrifices itself

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