edhseer Commander synergy, explained
Land
This land enters tapped unless you control a Swamp.
Add {B}.
activated {T} — adds 1 mana
Target creature you control connives X, where X is the number of creatures that died this turn.
activated {B}, {T} —
Causes: draw a card, discard a card.
Cares about: nothing.
a land enters the battlefield — 1,560 cards in the game can cause this (Spymaster's Vault is one).
When Spymaster's Vault enters:
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 (Spymaster's Vault is one).
When Spymaster's Vault makes a player discard a card:
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 (Spymaster's Vault is one).
When Spymaster's Vault makes a player draw a card:
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 (Spymaster's Vault is one).
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 (Spymaster's Vault is one).
When a card hits the graveyard thanks to Spymaster's Vault:
7 other cards care about it too. These are the ones with the most connections.