Yavimaya Dragster

Carpool - Whenever Yavimaya Dragster attacks,
you may tap an untapped elemental creature you control. If Yavimaya Dragster would deal combat damage to a player this turn, it instead deals that
combat damage plus X where X is the tapped creature's power.
Tap an untapped elemental creature you control: Yavimaya Dragster becomes an artifact creature
until end of turn.
Crew 3