Shadowfang Keep (Heroic)

by Whitelight

Interrupting Mend Rotten Flesh and Stay of Execution is mandatory. Pain and Suffering can be interrupted or dispelled.
It usually works best to assign one interrupter to each spell.
He periodically drops everyone to very low health. You can use self-healing abilities or rely on your healer's AoE. If you're having trouble with this mechanic, you can let Stay of Execution tick once, which will heal the boss and all group members for 10%.
When he enters Dark Archangel Form, he will start AoEing everyone. This is a DPS burn and a healing check.

Kill the adds as they spawn.
A healing mitigation debuff is periodically applied. When it's gone, keep the tank topped off.

This is the hardest boss in the instance but is optional.
The tank must keep him faced away from the group.
Currently, you can kite him back into the courtyard, where he won't summon adds. This will probably be fixed. If you're not using this glitch, read on...
The tank should have his or her back to the wall, moving from corner to corner to get out of the ground effect. Use the side of the room opposite the boss's starting position.
The adds should not be tanked. They should be CCed/stunned/interrupted and focus killed immediately.

When he creates a mystery toxin, which will start spraying around the room, you will need to notice which color it is.

In short: green means go, red means stop.

Unless you move during the green spray and stop during the red spray, you will be damaged significantly.