Necroduality

Whenever a nontoken Zombie you control enters, create a token that's a copy of that creature.

Metropolis Reformer

Flying, vigilance
You have hexproof.
Whenever this creature is dealt damage, you gain that much life.

Elesh Norn, Mother of Machines

Vigilance
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Permanents entering don't cause abilities of permanents your opponents control to trigger.