Originally Posted by
Kantalope
Accretion is stacked periodically throughout the fight on the monster that casts it, and on nearby monsters. Damage done to the monster reduces their accretion stacks, so it's best to keep everything stacked up and cleave to keep their stacks at 0. We tried splitting them initially, but with no damage being done to the other shard, his accretion stacks began to build up. I have a feeling they'll be stacked even on mythic since you can nullify the stacks by cleaving.