Bronjahm is the first encounter in the Forge of Souls. At intervals, Bronjahm channels "Corrupt Soul", which spawns a Corrupted Soul Fragment when completed. As these fragments heal him when they reach him, the usual strategy for the encounter is to destroy the fragments as they are generated.
For this achievement, four of them have to be alive when the boss is defeated.
The fragments are only generated during Phase 1 of the fight, when Bornjahm can be kited around to prevent the Fragments from reaching him. However, on entering Phase 2, Bornjahm teleports to the center and remains unmoveable.
Earning this achievement relies on the fact that the Fragments can be slowed, ensnared, etc. Kite Bornjahm to ensure fragments don't reach him, and ensure that the fragments are (or will be) slowed or immobilized away from the center of the combat area. Don't start phase 2 (by reducing him to about 30% health) until you have all four fragments up and usefully positioned. When Bornjahm teleports to the center, burn him down as fast as possible.
- Patch 3.3.0 (08-Dec-2009): Added.