Kakashi, The Copycat

Ninjutsu {3}{u} ({3}{u}, Return an unblocked attacker
you control to hand: Put this card onto the battlefield
from your hand tapped and attacking.)
Whenever one or more creatures dealing combat
damage to a player causes one or more triggered abilities of Ninja creatures you control to trigger,
you may have Kakashi, The Copycat gain one of
those abilities (Kakashi can't have more than one
of the same ability.)