Pumpwerks Engineer

Warcry - Each time a unit or Relic Weapon with Warcry attacks, it grants a permanent bonus to the top-most unit or weapon in your deck. Even if it's a few cards down, you'll get to stack up the bonuses on it over multiple turns.

Stealth - When you play a Stealth unit it will be Hidden from your opponent. They won’t be able to see what is, including its stats.