All heroes a 3/70 are fragile!
Right now I am raiding with a team that includes Tree, C Sabina, C Mel, Proteus… some of the most fragile heroes in the game. Winning most of the matchups, so there are definitely ways of offsetting fragility. If I had Lady Locke I would definitely use her, probably slotting her in with Noor/Gulli/Luigi for added survivability