I just defeated with 3 level 46.

I used the first 3 pets in my stables
Sweetpea, Amira and Meera.

I killed the middle one first, then when I killed the top one the bottom one disappeared.

I used about 5 of the 1,600 potions and 5 of the 400 potions and 3 return from death potions. I also healed everyone just before the battle.

Every time their mana was at 80% or better, I used finishing blow. Every time their Mend was off cooldown, I used it. I concentrated on keeping my tank alive first. Every other turn I used a potion. Except when one died in the same round I healed another. I had to wait a round to get the second back up.