The amber beams and shards of ice slam into the large form of Darkness, seeming to have an effect though visible damage is harder to decipher as his figure seems to almost flow about slightly.  The black orb sent downwards by Phaerys though seems to basically just meld back into Darkness' form as opposed to actually striking him.  The same can not be said though as Gulgrims large head and steel jaw colide with Darkness' face.  A loud sickening crunch can be heard as the large dark figure stumbles back a step or so, his face clearly looking damaged as black ooze seems to flow down to the ground.  At the same time, the demonic forces controled by Soul Reaver charge forward.  Even as his face seems to ooze what one could assume to be akin to his blood he simply smiles as he kicks out with one of his feet, striking Gulgrim and shoving the large Warboss back a few steps.  At the same time his two free hands extend towards the incoming demons as inky black tendrils shoot outwards.  The tendrils slam into the approaching demons and seems to almost curl around them as Darkness instantly drains the energy and life force from the creatures, causing them to quickly wither away into twisted husks, while a surge of power can be sensed from the dark pool.  An almost maniacal chuckle emanates from Darkness as his injuries quickly seem to heal until it looks like not even a scratch remains on him.  His gaze then turns towards Vee.

"They certainly put up a lovely fight...but I think more is needed.  You...are needed dear sister.  It has been far too long since we have spoke...has it not?"

Then, as if in answer to the question, a surge of pain erupts within Vee, her back arching as her mouth opens wide in a howl.  Brilliant light seems to erupt from within her, shooting out of her mouth and eyes, her body collapsing to the ground a second later.  The beams seems to form into an orb in front of her before suddenly flying back towards the golden crystal and seeming to crash into the damaged surface.  A second later the crystal flashes and pulses, the missing chunk filling in and the cracks disappearing.

"I knew it...so this was your plan all along."

Then the crystal flashes once more and disappears, replaced by a tall glowing figure of light.  Standing roughly the same height as Darkness the figure could be described as bearing hints of a female humanoid, though they only seem to presently have two arms, a glowing longsword gripped in the one and a large shield strapped to the other.

"You are correct...dear Brother."

"Your little trick last time was desperate for sure.  Escape our prison and for what?"

"An attempt to stop the Cycle perhaps.  Gain an edge against you finally.  I had hoped you were close enough to the edge to be unable to react...but I was wrong."

"Mmm that you were, and if you had been a little bit weaker you would have been unable to stop my response after you landed.  Instead of destroying that planet it simply scoured it.  In truth though it matters little.  You have seen the same things I have.  You now know the truth of what is outside of our prison and even our universe."

As the two figures are speaking, the Companions can sense something..different with both Darkness and the figure that almost certainly must be Light.  While the powers of the two entities are largely newly to the warriors, they can now sense hints of the Warp in both beings, like tendrils slithering through them.

"It was all pointless.  Light versus Dark, Order versus Chaos.  Win or lose, it is all pointless Sister.  We fought for eons to try and determine which of us was right..for what?"

As Darkness speaks, Light shifts on the other side of the platform, her gaze moving between each of the Companions.  One can almost see ever so faint whisps of Warp energy seeming to flow over her glowing figure, the effect standing out much more then compared to Darkness' inky black form.

"You may have a point Brother.  Regardless of which of us possibly wins and reforms this universe...there are so many others that are wrong.  Even the planet I landed on and...saved.  There is no hope of bringing Order to it anymore, or the countless other planets ive seen in my travels."

"Nor Chaos, or at least what I once saw as Chaos.  No...what dwells out there is well beyond such simplistic concepts."

Darkness is interrupted as Vee, still lying on the ground lets out a groan and manages to lift her upper half up as she glares at Darkness.

"It was YOU.  YOU are the one who practically destroyed my home and almost wiped out everyone on it."

Her gaze then turns towards Light, glaring still.

"And you...forcing me to stay silent while you hid away inside...and you knew all of this all along?!?"

Lights gaze shifts over to Vee but doesnt seem to display any sort of emotion.

"Not quite...the effort shattered my mind...only mostly reforming once I returned home.  I saw no reason in delving into things, I felt it a much better choice to bide my time until you finally got closer to the remainder of my figure.  Of course then things became clear.  Your people were sacrificed to preserve Order...though I now see that that was unnecessary."

Her gaze then shifts back to Darkness as he speaks once more, Vee seeming to falter and collapse back to the ground.

"Yes...unnecessary.  You agree then dear Sister, our original disagreements are paltry compared to the truth, to what needs to be done to bring true balance.  Come...let us deal with these "Companions" and then we shall work to bring true balance to the multiverse."

Both figures raise their respective weapons, awaiting to see what the Companions shall do against the might of both powers.

What Phaerys had initially assumed may have been a pocket dimension was in fact the top of a great tower amid a city of ebony. The Shaiton capital, he presumed, currently besieged by their allies. Almost a pity they were not here to study the architecture.

Against the oncoming beam of darkness, Phaerys launched himself skyward to evade it, projecting a wave of fire above himself to temporarily shield against the rain of dark orbs. He bought himself a few precious moments to hurriedly fabricate a shield out of alloys, hopefully allowing some margin for error as he steered himself away from more potential hits. Occasionally he was able to capture an orb in an orbit around himself, before flinging it back towards Darkness with considerably more force than it previously had.

Hovering round his vantage point from on high, it was hard not to notice the incongruous glimmer of gold some distance behind their foe. As if on cue, the Ataran heard Kitharsis' voice, echoing his own suspicions of the unknown object. Phaerys reached out and replied:

Hypothesis: Seraphim artefact, not Shaiton. Salvage, not sunder.

https://static.wikia.nocookie.net/finalfantasy/images/0/09/Another_Crystal.jpg/revision/latest/scale-to-width-down/1000?cb=20100706192806
For reference this is vaguely what the crystal looks like but is like laying on its side on the ground.  Also, its clear that Darkness isnt drawing any power or seemingly interested in the crystal, unlike the pool.  Kith if you want to tweak the end of your post to account ofr that go ahead

Even if he can't figure out the word-for-word meaning, Soul Reaver should be able to make out the gist of what the glyphs around the pool do.

The Steelheart's skin is essentially thick magical plate armour, so it should be able to weather the incoming attack while it shields Soul Reaver.

Alrighty, Gulgrim has two large swords swinging down directly at him, Kitharsis and Phaerys has beams of darkness directed at them and everyone has orbs of darkness raining down from above.  Everyone (sans Gulgrim as i figure he is too focused on Darkness to even see anything else lol) can see everything described, the enshrouding darkness now being completely gone.