Midnight Entity — Whenever this Vehicle attacks, defending player faces a villainous choice — That player sacrifices a creature of their choice, or you gain control of a creature of your choice that player controls until end of turn. If you gain control of a creature this way,
tapTo tap a permanent, turn it sideways from an upright position. Only untapped permanents can be tapped. (CR 701.26) it, and it's attacking that player.
CrewCrew is an activated ability of Vehicle cards. “Crew N” means “Tap any number of other untapped creatures you control with total power N or greater: This permanent becomes an artifact creature until end of turn.”
A creature “crews a Vehicle” when it’s tapped to pay the cost to activate a Vehicle’s crew ability.
A Vehicle is “crewed by” a creature if that creature was tapped to pay the cost to activate that Vehicle’s crew ability.
If an effect states that a creature “can’t crew Vehicles,” that creature can’t be tapped to pay the crew cost of a Vehicle.
Some Vehicles have abilities that trigger when they become crewed. “Whenever [this Vehicle] becomes crewed” means “Whenever a crew ability of [this Vehicle] resolves.” If that ability has an intervening “if” clause that refers to information about the creatures that crewed it, it means only creatures that were tapped to pay the cost of the crew ability that caused it to trigger. (CR 702.122) 2