Tremble is like a Bash+ that costs less, deals more damage (because you can play a good 1-Cost Attack as well), and has exhaust synergies as well as Vulnerable synergies. Don't take TOO many of these, but the vast majority of Ironclad decks are happy to have one or two. They enable good damage early on and then open up Vulnerable synergies very easily for the rest of the game.
