With control now not being an issue, the main question is usage. What can she possibly do with this power?
Thus far, the powers of Eldritch Energy have largely been similar to how divinity work.
Like the Icons that Alyss had fought before, the usage of Eldritch Energy was mostly seen in enforcing their laws, their authority, onto the world.
Direct usage of the energy seemed to be restricted to just the action of assimilation.
For Isolde, her usage of the energy was simplistic. It was fuel for her to unravel her body in a way and attack her enemies using the multiple limbs that she can control with lethal precision along with the poison she injects into them.
Paralysing them yet making sure they could feel everything.
On the other hand, Jin was more. . . Instinctual. Like Isolde, his Eldritch Energy is used to create darkened limbs behind him, helping him rip and tear away at whatever he wants to kill.
