Fatal Push

Destroy target creature if it has mana value 2 or less.
Revolt — Destroy that creature if it has mana value 4 or less instead if a permanent left the battlefield under your control this turn.

Secret Lair Drop

"Then I leave you in the hands of fate."
—Ezio Auditore

Assassin's Creed

Destroy target creature if it has mana value 2 or less.
Revolt — Destroy that creature if it has mana value 4 or less instead if a permanent you controlled left the battlefield this turn.

Secret Lair Showdown

Tokens that leave the battlefield will satisfy a revolt ability.

Fatal Push can target any creature, even one with mana value 5 or greater. The creature's mana value is checked only as Fatal Push resolves.

If a creature on the battlefield has {X} in its mana cost, X is considered to be 0.

Revolt abilities don't care why the permanent left the battlefield, who caused it to move, or where it moved to. They're equally satisfied by an artifact you sacrificed to pay a cost, a creature you controlled that was destroyed by Cast Down, or an enchantment you returned to your hand with Cyclonic Rift.