Roshi, Master Perv

Improvise (Your artifacts can help cast this spell, like convoke. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Ward {4}
Whenever an artifact enters the battlefield under
your control, put a +1/+1 counter on Roshi,
Master Perv and it can't be blocked this turn.
"You're looking at a martial arts master!"