Anashti Sul is rooted in place and must be fought on her pedestal. She does not summon, however if the primary aggro target stays out of her reach, she sends them a warning: Anashti Sul's voice echoes in your ears, 'If you won't face me, I'll rot you from the inside out!' She will death touch her target if they do need heed her warning after two fast emotes.
You cannot cast disease or corruption type spells of any kind on Anashti Sul, as they will heal her. This is only true for intentional spell casts or AA activations that check against disease or corruption. Weapon procs and sympathetic strike procs do not trigger this emote/effect. Anashti Sul, Damsel of Decay moans, 'Ahhh, that feels much better. I am disease and corruption incarnate, Yourname. You should be more careful with the magic you wield!'
Bokon believers and viscous piles of rot spawn at different intervals. Both are blue con at level 105, so forced movement abilities work for controlling them. The bokon should be fought and rooted on the bottom floor, and the piles of rot should be offtanked on the upper floor until your bokon are ready. The piles of rot are dragged above the rooted bokon, which cause the rot and all the bokon in that spot to die immediately. The timers for bokon and piles of rot are set up such that you will get fewer piles of rot than you will get bokon, so you will want to delay and kill multiple bokon at once. You do not want many bokon up at once due to the spells they cast: Bokon Blast (50K DD, single-target unresistable cast on multiple targets) and Enfeeblement (reduce spell haste by 66%, reduce movement speed by 66%, reduce melee haste by 150%, single-target unresistable cast on multiple targets).
At 75%, Anashti Sul begins casting Gifts of Anashti Sul on random players in the raid on a decaying timer. At first she casts them every 35 seconds, but will switch to every 30 seconds, and eventually to every 25 seconds. The Gifts are an AE around the targeted player and there are two possible gifts. Gift of Endless Life is a Heal over Time (15K HPs) with 1 curse counter. It is NOT intended to be cured. If Endless Life is cured, the curer loses all mana/endurance and eats a 100K DD. Gift of Living Death is a large nuke and Damage over Time (100K DD and 75K DoT) with 29 curse counters and should be cured. It is very important to only ask to be cured for Living Death. If you happen to get both Gifts, ask to be healed through the duration until Endless Life fades.
At 55%, Anashti Sul teleports to the lower floor and strips all debuffs: Anashti Sul laughs, 'I am not even there!' This starts a timer where she will begin switching floors every 1 minute and 50 seconds. A trap of sorts also begins spawning directly on top of random players. A writhing rotting mass slithers from beneath you. The gangrenous grabber looks like a mass of branches, roots, or tentacles. It generates an aura that you do not want to stand in because it pulses damage once per second (50K DD). You are lashed by tendrils of pestilence. The traps cannot be killed and will despawn after some time.
At 35%, Anashti Sul begins casting Withering debuffs on random players. If the Withering debuff wears off or is cured, then a new Withering debuff takes its place. This rotation of Withering debuffs continues as long as you remain in the zone. The debuffs are Withering Limbs (reduce melee and spell damage by 100%), Withering Faith (reduce healing by 100%), and Withering Physicality (increase damage taken by 2560%). The Withering debuffs are only 29 disease counters and are intended to be cured so that you rotate to a debuff which does not have a detrimental effect for your class' role. Tanks should not have Physicality, priests should not have Faith, and DPS should not have Limbs.