Masked Assassin

When Masked Assassin enters the battlefield, you may destroy target creature with converted mana cost three or less.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)
The assassin only follows his targets. If you've seen him twice in one day, then your time has come.