edhseer Commander synergy, explained
Instant
Mana cost: {1}{G}
If this spell is the first spell you've cast this game, you may cast it without paying its mana cost.
on-cast —
Look at the top five cards of your library. You may reveal a creature or land card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
on-cast — searches a library
Causes: cast anything.
Cares about: nothing.
an instant is cast — 3,931 cards in the game can cause this (Once Upon a Time is one).
When Once Upon a Time is cast:
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 (Once Upon a Time is one).
When Once Upon a Time is cast:
5 other cards care about it too. These are the ones with the most connections.