Each creature you control is an artifact in addition to its other types and has Clockwork X, where X is the creature's power. (It enters the battlefield with X +1/+1 counters. At the beggining of your end step, remove a +1/+1 counter from it. When it has none, sacrifice it.)

Whenever a creature enters the battlefield under your control from exile, it gains trample and haste until your next turn.