Exploratory Vessel

Crew 1 (Tap any number of untapped creatures you control with total power 1 or greater: This permanent becomes an artifact creature until end of turn.)
Whenever you activate Exploratory Vessel's crew ability, if creatures with total power 4 or greater were tapped to activate it, Exploratory Vessel cannot be blocked this turn.
Whenever Exploratory Vessel deals combat damage to a player, draw a card.