edhseer Commander synergy, explained
Legendary Creature — Human Berserker
Mana cost: {3}{R}
Trample
Whenever another creature you control enters, Arni gets +X/+0 until end of turn, where X is that creature's power.
triggered — gives +X/+0, where X is that creature's power
Causes: nothing.
Cares about: a creature enters the battlefield.
a Human enters the battlefield — 661 cards in Arni's colors can cause this (Arni is one).
When Arni, Renowned Champion enters:
a creature attacks — 3,451 cards in Arni's colors can cause this (Arni is one).
When Arni, Renowned Champion attacks:
58 other cards care about it too. These are the ones with the most connections.
a creature blocks — 3,451 cards in Arni's colors can cause this (Arni is one).
When Arni, Renowned Champion blocks:
1 other card cares about it too. These are the ones with the most connections.
anything attacks — 3,451 cards in Arni's colors can cause this (Arni is one).
When Arni, Renowned Champion attacks:
19 other cards care about it too. These are the ones with the most connections.
a creature is cast — 3,468 cards in Arni's colors can cause this (Arni is one).
When Arni, Renowned Champion is cast:
10 other cards care about it too. These are the ones with the most connections.
a nontoken creature enters the battlefield — 3,511 cards in Arni's colors can cause this (Arni is one).
When Arni, Renowned Champion enters:
a creature enters the battlefield — 3,801 cards in Arni's colors can cause this (Arni is one).
When Arni, Renowned Champion enters:
57 other cards care about it too. These are the ones with the most connections.