Both Jajin and Cheeks have individual health scores that someone or two in the party must keep track of. Once one sister receives enough damage to jump into the next phase do so even if the other sister is not at that level of health.
They do not have modifiers, and players simply deal direct damage to them. Any spells that need the targets mod to effect the spell (or anything else) they are immune to.
Notes on how they attack.
The re-spawn rule in the rule book doesn't count in a boss fight. If you die, you must wait until your group wipes for you to come back. All party members come back at full health.
Combat Mulligans are void against this boss fight. Non-Combat Mulligans allowing a Pre-Fight advantage are void as well. Only mulligans affecting a players Skills and Spells can be called. (Ex: Rogue calling a shadow to gain a stack using a Non-Combat Mulligan is allowed)
Notes on spells cast on the Sisters.
All stuns / fear spells, skills, auras, anything (where the targets runs away, is blinded, or can't attack); they are immune to.
Notes on attacking the Sisters.
If any kind of attack or spell attempts to hit both sisters in one combat round by the player, the second attack the second sister becomes immune to.
Examples: Duel Wield and Wide-Strike.
Notes on Countering the Sisters "SPELLS":
The sisters "Spells" and their "Chants" are classified as spells. Their Abilities are not spells and can not be silenced, counted, or negated as if they are spells.
Battle order: Jajin goes after Player 1, Cheeks goes after Player 2. During the sister's attack phase, roll 1d4 to determine which spell is cast AND roll 1d4 to determine which ability is active.