The current Oracle wording of Sneak Attack is: "{R}: You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice the creature at the beginning of the next end step." (underlines by me).

What if I use Sneak Attack to put a Clever Impersonator onto the battlefield and let him be a copy of something that's not a creature, e. g. a planeswalker? Do I have to sacrifice him anyway at the end of the turn?

I know that there are abilities that refer to the same card even if it has not the same type in the new zone, like an animated land or artifact dying and triggering an Enduring Renewal which returns it to my hand. But in these cases, the word “it” makes it easy to understand that the ability is refering to the card, whatever it is until then.

Is this applicable to abilities that explicitly refer to the “creature” instead of “it”? Will Dread Slaver or Grave Betrayal make the Clever Impersonator black even when he's not returning as a creature?

Yes, it will still be sacrificed at the end of turn, due to this rule:

603.7c A delayed triggered ability that refers to a particular object still affects it even if the object changes characteristics. However, if that object is no longer in the zone it’s expected to be in at the time the delayed triggered ability resolves, the ability won’t affect it. (Note that if that object left that zone and then returned, it’s a new object and thus won’t be affected. See rule 400.7.)
Example: An ability that reads “Exile this creature at the beginning of the next end step” will exile the permanent even if it’s no longer a creature during the next end step. However, it won’t do anything if the permanent left the battlefield before then.

You picked a creature card in your hand, so the Attack's delayed triggered ability will still affect it, even though it's not a creature when the delayed trigger resolves at the end of the turn.

In the case of Grave Betrayal (and Dread Slaver), if you don't copy a creature with the returning Impersonator, it will get the counter from the Betrayal and it will become black (since those aren't reliant upon it being a creature), but it will not have the Zombie creature type (since it's not a creature).

Nathan Long
Wizards.Com Boards NetRep