Crystal Stars: crystal that does AOE degen. 1 spawns in each invulnerability phase and can be detonated with Explosives to disable.
After each damage phase, Olroth becomes invulnerable and spawns both a mirror like portal and a crystal. The portal will spawn endless minions while the crystal will have a righteous fire aura which will pretty much insta kill you if you are standing near it. Kill a few of his minions and Dannig will say use the explosives. He will spawn two explosives which lead to either the portal or the crystal. In order to get either achievement you need to explode either the crystal or the portal for each transition phase. More specifically, explode both portals or both crystals which will leave either two portals or two crystals during his final phase.
During the invulnerability phases, destroy both Gateways; this will mean the remainder of the boss fight will have the crystals and their damage over time around them.
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