Xefyr, Clockmaker Supreme

Flying, Vigilance
Whenever an artifact enters the battlefield under
your control, up to three target creatures you
don't control get -1/-1 until its controllers next
end step; if a creature an opponent controls
dies this way, draw a card.
{x}{x}{u}{b}{t}: create X 1/1 colourless artifact owl
creature tokens with flying and "{t}: add {u}".
"Tick tock..."