Yeah I'm kind of squishy, but I am a bit of a nuke. Even though I'm basically free to play (I've only spent $3), I was able to beat guys a couple levels ahead of me until I hit the "barriers" (level 45 in the arena and level 50+ summons in other instances). I'm not fully sure what resistance does fully. I assumed it would give a chance for debuffs to not effect you, but I'm not completely sure.