edhseer Commander synergy, explained
Instant
Mana cost: {U}
Cast this spell only during an opponent's turn, before attackers are declared.
Creatures the active player controls attack this turn if able.
At the beginning of the next end step, destroy all non-Wall creatures that player controls that didn't attack this turn. Ignore this effect for each creature the player didn't control continuously since the beginning of the turn.
triggered —
Causes: a creature dies.
Cares about: an end step.
anything leaves the battlefield — 1 card in the game can cause this (Siren's Call is one).
a creature in a graveyard — 2,769 cards in the game can cause this (Siren's Call is one).
Siren's Call puts cards into the graveyard that:
799 other cards care about it too. These are the ones with the most connections.
a nontoken creature dies — 2,769 cards in the game can cause this (Siren's Call is one).
When a creature dies thanks to Siren's Call:
60 other cards care about it too. These are the ones with the most connections.
a creature dies — 2,830 cards in the game can cause this (Siren's Call is one).
450 other cards care about it too. These are the ones with the most connections.
a creature goes to a graveyard — 3,011 cards in the game can cause this (Siren's Call is one).
When a creature hits the graveyard thanks to Siren's Call:
8 other cards care about it too. These are the ones with the most connections.
an instant is cast — 3,931 cards in the game can cause this (Siren's Call is one).
When Siren's Call is cast:
427 other cards care about it too. These are the ones with the most connections.
a nontoken creature leaves the battlefield — 4,133 cards in the game can cause this (Siren's Call is one).
When a creature leaves the battlefield thanks to Siren's Call:
a creature leaves the battlefield — 4,238 cards in the game can cause this (Siren's Call is one).
28 other cards care about it too. These are the ones with the most connections.
a permanent is put into a graveyard from the battlefield — 5,057 cards in the game can cause this (Siren's Call is one).
15 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 (Siren's Call is one).
441 other cards care about it too. These are the ones with the most connections.