I searched for this but I didn't find anything...just other deep freeze things. (There is one about the frostbolt / spam Deep Freeze but i didn't think this was a repost. Sorry if it is)
Anyway, Every frost mage knows Deep Freeze and its 5 second frozen stun. well i was bored and saw a pally (13k hp) ((ya im not lvl 80 *GASP* only 71))
Begin the fight:
Summon elemental
Start casting frostbolt and just before it casts. Use the elemental's freeze spell and after frostbolt is cast. Spam the crap out of Deep freeze.
(BUT you may want to cast another ice lance because freeze will stay have about 6 seconds left. NOTE: Lance may break the freeze)
This will Freeze them for 5 more seconds (yay)
Cast ice lance TWICE. ONLY TWICE. (if they dont trinket out of this) pop cold snap and re-deep freeze (SPAMMING NEEDED HERE!) (macro if no global CD?)
Use Ice lance as many times as you can get off before it ends. (Ice lance can do more damage here than casting frost bolt then using ice lance)
Target will be atleast close to death. So just use Fireblast or other instant / Quick casts.
I did about 12k by the end of this barrage to the pally and then just fire blasted him once.
(GUESS): at level 80 and mirror image, you should be able to completely obliterate them with this. (hopes for no trinkets)
Hope this helps