Downpour

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

When a creature becomes tapped thanks to Downpour:

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.

anything becomes tapped — 699 cards in the game can cause this (Downpour is one).

1. Master Pakku — When Master Pakku becomes tapped thanks to Downpour, it mills a card

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

an instant is cast — 3,931 cards in the game can cause this (Downpour is one).

When Downpour is cast:

1. Lunar Mystic — draws you 1 card
2. Ojer Pakpatiq, Deepest Epoch // Temple of Cyclical Time — grants rebound
3. Repeated Reverberation — copies an ability
4. Riku of Two Reflections — copies a spell
5. Sword of Wealth and Power — copies a spell
6. Lilah, Undefeated Slickshot — gets +1/+1
7. Gale, Waterdeep Prodigy — brings a card back
8. Harness the Storm — brings a card back
9. In the Eye of Chaos — counters a spell
10. Niblis of Frost — taps a creature an opponent controls

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

anything is cast — 31,128 cards in the game can cause this (Downpour is one).

When Downpour is cast:

1. Windrider Wizard — draws you 1 card
2. Relic Amulet — puts a charge counter on itself
3. Rockslide Sorcerer — deals 1 damage
4. Umara Wizard // Umara Skyfalls — grants flying
5. Alania, Divergent Storm — makes an opponent draw 1 card
6. Umara Mystic — gets +2/+0
7. Master of Winds — triggers

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