we done it slighly different last time.
began as mentioned above, 4 stacks, dps go.
then let fall off the debuff, me as Holy got 2 adds with the single-target taunt, and a HS at the second add. (+ healaggro)
Our tank taunted the 3rd.
killed the 2 adds outside, then focused the 3rd near the boss.
got 2-4 stacks because of the lava-shit, pull boss out, dps go.
Repeated this till the end.
This is kinda easy to handle, esp. if your group is not that geared up.
Adv.: there is no to little aoe dmg on grp, so Healer ( me xD ) can focus on healing the tank.
Fight lasts little longer, but u need nearly no grp-heal and u get the struggle out of the fight.
regards