kill whatever is in a good position to be killed. It's always nice to blow up the pet if you can prevent resummoning. Cover sheeps with winter's chill (esp against paladin+wl) and try to end the match as fast as possible... otherwise 2k dot ticks will kill you. as to destruction wls: kill the healer.
hm depends. depends on how bad the paladins positioning is. if he pillarhumps, just dispel warrior, nuke him with deepfreeze n everything while pally is sheeped. interrupt during auramastery with sheep+df. if you time burst and cc well you should be able to force shieldwall and/or bubble + aura mastery. always steal sacrifice and freedom, block bladestorm. you can also easily kill a prot paladin open field with a well timed deep freeze.
Eltari, thanks for responding to so many posts. Mage/Mage is a super fun comp. We are having a bit of trouble against Pally/Unholy DK as we get higher rating and are starting to see more of these comps. Your words?
We've only faced Unholy / Prot which was kinda hard. I guess the safest way is to get paladin sheeped and nuke dk to force ams/amz/strangulate/whatever. Considering the paladin got aura mastery, trinket, holy shock and bubble you really need to be able to survive the dk's dmg output until they've used all of their defensice cooldowns - meaning you should always be ready to support your mate by peeling the dk. If need be with the aid of deepfreeze/cs/poly.