"YOU BETTER DIE TO MY MINIONS BECAUSE YOU'LL WISH YOU DID IF I COME FOR YOU!"; "DESTROY THE INFIDELS"; "You are mine!"; "I will make you all pay!"; "No one will stop my plans!"; "You are responsible for this!".
Runs at very low health (only if health bar is entirely black).
One strategy is to use the south-east corner of the room as a retreat-point when a lot of monsters are summoned. First make sure to kill all the summons, then trap Yakchal with an Energy Bomb Rune, so she won't move. Then finish her off with SD:s. Another strategy is having 1 person awaken her, and then rush to the south doors. Use a Frozen Starlight on the sarcophagus to awaken her (The Frozen Starlight can break when it's used on the sarcophagus to awake the Yakchal, but mostly it won't. Also keep in mind that you can awaken her more than once per day. After every floor reset, you will have a new chance to summon her.)
Make sure somebody blocks respawn on the other side, otherwise there could be a Demon, Plaguesmiths and Nightmares. If you're fast enough, you won't have to go to the other side of the door to be safe from the most of the creatures that will spawn with the awakening.
From those doors, you can then slowly lure all creatures one by one, and sooner or later Yakchal will come too. Unless your team has a lot of firepower, try to trap her in a corner somewhere, she will run away in very low health.
Shoot at her with Sudden Death runes and/or Assassin Stars.
Be aware that she will disappear in (approximately 10) minutes after the awakening!