So when I ran this instance at level 104-ish with my 4 Blood DK - Holy Priest group (each with one 945 legendary item, otherwise level-appropriate gear) I was able to clear it without too much trouble.

However, at level 110 (with ilvl 815-ish), I am banging my head against this encounter. I can get through 3 waves of the Horn of Valor AE but through attrition, I eventually lose.

I think it boils down to DPS, but I'm not sure how to improve it. Artifact grinding?

Any help would be appreciated.