I didn't even know about the fire doing damage to the mobs, so I didn't make use of that. That said,
Remoreseless Winter on the adds that enrage such that it stuns them before they enrage. They're immune to the stun when enraged.
Asphyxiate is a strong talent choice for single-target breathing room. You can use it to stagger the big guys so they're not enraged at the same time.
Glyph of regenerative magic (I didn't have it, but it's probably the best glyph for proving grounds as it'll let you run over more fire or take a few extra errant spells).
Kill priority: Ambushers>Big guys>casters (but keep interrupts/AMS up while working down other things)>knockbackers>pawns
Use death grip as yet another interrupt on casters, rather than as a taunt on other mobs.
I saved army for the 10th, and popped it just as the wave started--I didn't want to spend the time channeling when mobs were up.
I wore one stam trinket and one dps trinket, rune of FC, dps meta, dps cloak, mastery/haste build.
I remember getting the 10th wave with lots of sloppy mistakes and inefficient kill priority. Running away from mobs when it got hectic helped to give me some breathing room, but I'm not sure a more responsive/proactive tank would have needed to do so.
dont hesitate pulling cooldowns, wisely use death strike
i actually regemmed/forged to avoidance, used a stamina trinket and engi trinket with 3 cogwheel gems
made a huge difference compared to my hit/exp,mastery gemmed/forged gear, got to wave 37 in 4 attempts
/edit as for the kill priority, the npc already does that just focus her target
i got to around wave 34, but haven't tried again since (i just wanted "the proven defender" title lol). trinks/gear don't matter as much as proper cd usage. like people said before waves 2,6,9 are the hardest, then it starts all over again and round 12,16,19 will be the hardest, only difference is the mobs hit harder...
using army at the end of wave 8 is a huge help. by the time you get to wave 18 you can use it again.