Syndicate Agent

Skulk (This creature can't be blocked by creatures with greater power)
Extort (Whenever you cast a spell, you may pay {w/b}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever Syndicate Agent extorts, you may have it get -2/-0 until end of turn. If you do, it gains "{w/b}: This creature's base power becomes 4 until end of turn."
When Syndicate agent deals combat damage to a player, you draw a card and gain 1 life.