Since Clever impersonator would be entering the battlefield as a copy of any non-land permanent on the battlefield, would I be able to copy someone else's Ulamog and exile 2 nonland permanents and use the ability that says whenever Ulamog attacks, defending player exiles top twenty cards?
The exile ability triggers when you cast Ulamog, not when it enters the battlefield.
You cast Clever Impersonator as Clever Impersonator. It only becomes Ulamog as it resolves and enters. C.I. didn't had the ability when it was cast, so it can't possibly trigger.
But once it is on the battlefield, it has all of Ulamog's ability, including the attack trigger.
Private Mod Note
():
Rollback Post to RevisionRollBack
To post a comment, please login or register a new account.
Ulamog, The Ceaseless Hunger
Clever Impersonator
You cast Clever Impersonator as Clever Impersonator. It only becomes Ulamog as it resolves and enters. C.I. didn't had the ability when it was cast, so it can't possibly trigger.
But once it is on the battlefield, it has all of Ulamog's ability, including the attack trigger.