What gear are you using now? What is your deck setup? What method are you currently using to try and fight mobs in general?
Can't really give you helpful information if I don't know.
What I can tell you right now is to keep your deck for mob fighting slim (i.e. Don't use up all 64 slots in your deck when you're only going to use 9 cards) and use either Frost Giant or Snow Angel for your aoe.