Cetishil fires her heavy crossbow at the elf with the heavy crossbow. (Attack roll 15+4=19. Damage 3)
(You have all the buffs from before BTW, Cetishil never removed her essence.)
Edit: Fixed.

(101, remember to roll for damage at the same time you make an attack.)

(How far away are they?)

(About 20 ft. or so. It'll take you just one move action to get into melee of any of them.)

Burnish walks up to within fifteen feet of the both of them, and exhales his flaming breath to set both of them alight.

Breath Weapon: 8 damage, half on Reflex save DC 16
Can use again in 2 rounds

(Ref: (17) + 5 = 22.)

The elf with the duel hand crossbows drops to the floor by the combo attack by Shanara and Burnish.

Cetishil's bolt hits the other elf, who then moves to the other side of the room away from Shanara and Burnish and fires two crossbow bolts towards Cetishil as she's the only one within 30 ft. now. (Attack 1: (12) + 1 = 13, Damage: (6) + 1 = 7. Attack 2: (4) + 1 = 5, so not going to hit.)

Burnish growls, flying into the air and trying to charge down the elf.

Charge Attack: 25
Damage: 9

And with that, Brunish manages to fell the last elf in the room.

(You each gain 270 EXP and you find as loot a heavy crossbow, a masterwork chainshirt armor, a dagger, 2 hand crossbows, a masterwork leather armor, a longspear, and 58 GP in other goods and jewels.)

Shanara flared her wings in victory, eyes scanning the room for more targets. Seeing none, she checked for other passages up or down in the tower, to make sure they weren't leaving any guards unslain.

Other than the stairway heading up that was next to the wall and curving along the wall, Shanara found no other stairs up or down in this room.