Spoiling For A Fight

You do not receive quest credit in a raid group.

Do not switch shards after accepting the quest. Sabriel will not spawn if you do this.

Edit: Sabriel always spawns in place of Azmogal on the northwest side of the arena.

I joined a "Looking for Necrolord for Sabriel" group, which phased me after accepting the quest and we killed 10+ combatants without it spawning. I left the group, abandoned the quest, and relisted on my own realm and she spawned after about 2 kills. I did not get credit since it was a raid group, so I left group and reaccepted the quest again and she spawned after about 3 kills.

I may be wrong but that is my experience and I hope it helps someone.

1. Active Theater of pain by channeling your rank 3 condutor to it.
2. Accept the daily quest "Spoiling for a fight" at 54,48 in Maldraxxus.
3. The quest giver will put Sabriel the Bonecleaver into the rotation. Had to kill 5 contenders before he was put into the arena.

If you happen to kill Sabriel before picking up the daily, then Sabriel will not spawn no matter how long you stay in the arena. You need to talk to Au'narim after picking up the daily and before going into the arena and ask him to respawn Sabriel, and then she will come back up on the next rotation.