Night Claw, Uncatchable Thief

Night Claw, Uncatchable Thief can't be blocked.
Whenever Night Claw, Uncatchable Thief
attacks, you may gain control of target
non-creature artifact with converted mana cost
less than Night Claw, Uncatchable Thief's power
until end of turn. If you don't create a treasure
token. Whenever a artifact token enters the battlefield under your control, Night Claw, Uncatchable Thief gets +1/+0.