I think Mode 1 is underwhelming. Ideally, the card should be played when the tower gets below 10, and that puts the player to a big risk (considering it as a counter to -tower decks, cause against attack mode 2 is always better).
My point is that you can play it at 0 wall gaining 26 and 0-5 tower with mode 1, but can't play it at tower 0. Gaining 22 tower for 5b uncommon is very good, but very, very situational and risky.
I feel like the amounts should be reversed (wall = 18, tower = 21), and modes will become more equal in power and utility.