HELP FOR RANKUP AND AWAKENING GEM

Bucky_7

I have just started act 4,whom do I rankup next. I have a science and tech awakening gem,is it worth using on sentinel. And any advice on the champs

BrudixTree

I would use the gem on sentinel, makes fights easier and faster, but dont use the science gem.
You should r3 sentinel and Massacre, both great champs!