Remove any damage shield buffs you may have before engaging.
Vishimtar hits for ~4000; AE rampages (mitigated to ~1000); enrages; and casts Shadow, Aura, and Withering Corruption throughout the event.
After a random amount of time passes after being engaged (~3-6 minutes), tainted eggs begin spawning at somewhat random intervals (~75-120 seconds). Only blunt weapons have an effect on eggs. If they are not killed in good time, several corrupted drakelings (hit for ~1200; flurry) will spawn.
Four corrupted drakes get into the action at 50%. They are snareable and should be kited, as they respawn immediately upon being killed.
Beginning at 25% health, Vishimtar begins casting Creeping Doom at 45 second intervals. Four random players will be hit at a time. This spell must be cured within ~48 seconds of it hitting otherwise the affected player will be deathtouched. To cure, say "shoulder my burden" to one of the mournful spirits roaming the perimeter of the cavern.
For each player cured of the DT, Vishimtar can be damaged another 1%.
If anyone dies, or goes linkdead, at any time in the event, a spirit wraith (mezzable; hits for ~1500) will spawn in their place (this does not include pet deaths).
Killing a cloud of concentrated chaos will fill up everyone's health and mana.
Following Vishimtar's death, his AE effects will wear off and all adds will despawn. A chest with additional loot spawns.
Vishimtar roars furiously, 'Who would dare encroach upon our home and disturb the nest? I must protect the eggs.'