PRR GG1

Crew 2 (PRR GG1 can't be crewed by token or
artifact creatures)
When PRR GG1 attacks, tap X Wagons. Then,
PRR GG1 gains a +1/+1 counter until end of turn
for each X. If X is 4 or more, PRR GG1 gains indestructible and menace until end of turn.