Q: I activate and resolve Skyship Engineer’s Exhaust ability. Then, I use Eitan, Exiled Prince to sacrifice a 3 cost unit. When Eitan’s ability resolves, can I put a 5 cost Airship into play?
A: No. Skyship Engineer affects the “cost to play” of the Airships, not the actual cost. If you are not playing the card, it still has the same cost for the purpose of Eitan’s ability. (See cost to play – 9.4.7)