Been some time since the Proving Grounds, but my best try was 5,885.
My reforges: Hit/Exp (6,5%) > Mastery > Parry > Dodge
Used the 489 stamina trinket and the mastery trinket from Horridon.
Gear with a lot of gem sockets work the best, if you can get one try to get a weapon from ToT (for the extra gem socket).
- Roiling Blood
- Death's Advance
- Death Pact
- Blood Tap
- Remorseless Winter
- Glyph of Regenerative Magic
- Glyph of Icebound Fortitude (Failed to pay attention, don't want to die in a stun)
- Glyph of Death Grip
I got to about wave 56 recently. I would have gotten even farther had I not hit the wrong button for Death Pact (whoops). I was lazy and kept my same raiding gear on that I always do, so Hit/Exp caps > Parry > Dodge > Mastery. Remember that the legendary procs (both gem and cloak) and set bonuses don't work, so change your gear accordingly. I still wore the legendary cape because of its spread of secondary stats, but make sure to wear a helmet with the Austere Primal Diamond in it. Wear gear with tons of sockets. I used Vial and Rook's as my two trinkets.
Remorseless Winter is extremely important. Use it as much as you can to kite and stun to save yourself precious damage. Everything can be stunned except for the enraging big dudes.
Do NOT glyph Army of the Dead. Use it on wave 6 or 9 to let the ghouls tank for you. I don't recommend glyphing Icebound Fortitude like the poster above. There are not any big single hits that requires the decreased cooldown. It's more important to use it for the Enrages.
Pretty much what the above poster said, my highest is 54 and I forgot to use the old style meta. waves 6 and 9 are the most hardest, i prefer to use army on the 6th.
Use 2x stam trinkets with decent on use/proc defensive uses. The old shado pan trinket that has on use mastery is very good. Obviously use remorseless winter.I also took asphyxiate to help on the mantid adds since they have a lot of hp, and hit very hard at high waves.
If you're a frost dk like me you might not have to change your gear much. I did it in my dps gear (gemmed with mastery because of DW frost) and two stamina trinkets. Picked up the 463 one from Mogushan Palace and bought the 489 with mastery use (60 sec cooldown, good stuff!). I saw a video on youtube and noticed the dk in the vid used Fallen Crusader and str flask so I went with that (forgot to change meta) and reforged mastery > hit/exp caps > haste. Remorseless Winter, Purgatory, Asphyxiate and Death Pact were all very helpful in PG and are pretty much mandatory.
Now getting the title itself was much easier than expected. I face tanked most mobs with small cooldowns and used Remorseless Winter to kite when things got messy. I used Asphyxiate to stun the banana monkeys and the big insect men that knocks you back, and picking adds off the npc was no problem thanks to Death Grip. Just make sure to never panic and pop all your cooldowns at once, and always keep a Death Strike as backup just in case. Oh and run over fire with AMS to get more RP! As a death knight you have tons of "oh shit"-buttons, just try to not blow them all at the same time.