I use rock gronch in the arena because he is a beast if you can make him big on turn 1. He’ll wipe out a bunch of enemies and charge up from the kills. If he survives until his attack that’s most of the match won. I’ve found him a bit more variable in the other game modes, but still generally very solid.
I’ve also noticed something a little counterintuitive when your big creatures attack. For example if they are facing 2x strength 4 walls on the same row, then they will only lose 4 strength to destroy them instead of 8.
My minor gripe with the game is the daily chest grind, specifically the 5 quest wins component. If I’m stuck somewhere I go and grind some early quests but it’s not particularly fun. Does anyone have any suggestions for the most efficient/cost effective/rewarding way to satisfy this quest every day?