Vezax hard mode isn't that hard. It's mainly a matter of of finding the good balance of stamina and dps to kill him without having to change pets too often. In my video I had 2 stamina trinkets and a dps flask.
Strategy is the same as ever when the animus isn't there:
-avoid the black puddles
-avoid the shadow crashes
-Kite him for his "big mode" (blood of Yogg-Saron)
-interrupt one AoE out of two, use a pet CD for the others.
When the animus spawns:
-it will interrupt his big mode, so no need to kite him.
-Misdirect the add on your pet.
Vezax will stop casting his aoe, so use pet CDs as you like, intelligently (meaning, not during the kiting phase). If you attract aggro from the animus, better kite him a bit - anything to reduce pet incoming damage.
DBM won't warn you anymore for the shadow crashes, so open you eyes (Vezax turns toward you and launches a purple bolt: move).
Once the animus is dead, continue normally.
If you kill him before he berserks, you win.
Loatheb 25 is "yay look at me I'm topping the charts!" No strategy, just plain gear/rotation check. He has a 12-minutes berserk, so 28.1K dps is needed.
Unlike me, if you try him you should remember that stamina scrolls exist to be used in fights where your pet lacks survivability.
So: You have +50% crit chance. Since it affects everything, Chimera shot is a dps boost even during careful aim. Use an aimed shot rotation.
For your pet to survive, use a scroll of fortitude II, and use CDs as soften as possible, remembering to throw a heal when the debuff is ending.