How to play THM in a stronghold party:

Buff your teammates.

Wait for the tank to pull everything.

When you see that all the aggro mobs' names are red, and that the tank and/or the other melees have at least done around 100 or do damage to all or most of the mobs, cast stoneskin II on the tank.

Cast paralyze on the mobs.

Cast slow on the mobs (optional).

Cast Banish II or Scourge II ( the tanks and DDs should have generated enough hate by now that you should not grab hate. If your spell does 200 damage, then as long as someone else did 200+ damage to that mob, you won't get aggro).

Keep nuking.

Recast stonekin II on the tank whenver you can.

Cure the tank or anyone else who needs it.

When the mobs have about 20% HP left, Chainspell > Shadowsear.

Use profundity, blood rite, and dark seal when applicable.

Use invigorate to generate TP. Use Shadowfall in a group to generate an instant 3k TP if there are enough mobs.

Use Second Wind II to heal yourself in a pinch.

Use Leg Sweep to stun the mobs.

Do it right, and you can outparse shitty MRDs.