Isaac listened to the excuse, deciding to look into what he could do later. Not for explicit hunting purposes, nor for aid, but mostly just to see what he was working with. Demons, spirits, what have you, he had seen a lot of things that could be done. This person wasn't an enemy... as far as he could tell.
When the Heartless appeared, he glanced from one to another, then to another in turn. The larger ones seemed to have a very stabbable face in front of their towers, but likely used a lot of magic through the bulk of the entire thing. Good for mages or very up-close-and-personal fighters. However, Isaac was more concentrated on the one before him, the centaur of sorts. As Almadel had indicated, it seemed to be focused on him in particular. Perhaps it saw him as more of a threat, or as an easier victim?
The first thought was flattering. The second? Well, he just saw that as faintly amusing.
As the
Assault Rider charged forward, its halberd held out, he stood relatively still as it slashed hard across the gray-haired young man. The opponent just barely dodged a serious injury, but did get a cut on across his forehead, one that bled down the right side of his face, barely missing his eyes, but still looking severe, though not too bad for him. He stumbled backward a bit, making a show of it... and smirked a bit wider than before.
"You done?" Isaac asked, crackling black energy coming to his grasp. If David were close enough, he could have smelt something akin to the stench of death and rot, if he had even had experience with such things to know.
The Heartless horseperson roared, and charged in his direction, this time spinning its weapon back and forth, flourishing it in a windmill pattern to try to get a stronger hit in.
"Good." The crackling power coalesced into the form of an odd sword. It was dark brown, nearly black, and appears to writhe in a manner more similar to a wielded tentacle attached to a hilt than a blade in and of itself. There was a violet stone in the pommel that looked akin to an eye, which seemed to almost blink momentarily on appearance. As the beast came closer, he moved to the side, faster than before, and held the blade behind him, over his shoulder, as if sheathing it in some invisible location... and raked it across his back, drawing a thin line that began to bleed. As he did, it sparked to life, beginning to glow with a bright, white light across a channel along the blade itself.
Isaac slashed out with the weapon, hitting one of the legs of the Assault Rider with the power of light itself. It stumbled, angered ever more, and tried a thrust in his direction. This time, he was ever more ready, and muttered something under his breath in some arcane tongue. He could feel the blood coming from the marks on his body, those hidden by his clothes, but did not care overmuch about that.
What
did matter was that whatever he had been doing, it had no effect on the creature before him.
"Damnit," he muttered under his breath, and concentrated harder, muttering again. The drips down his back fell faster, the glowing blade in his hand stiffening to a normal appearance of a sword, as the wounded Heartless turned to face him once more. It came forward, hooves pounding the stone as it charged...
...and some kind of fluid, perhaps blood from such a bloodless being, fell before its eyes, rendering it momentarily blind. The confused Assault Rider kept running forward, slamming into a rocky outcropping as it swung the halberd back and forth in its confused blindness.
Isaac took the opportunity to lash out with his weapon, the Scion. Instead of acting as a sword, it lengthened, becoming more in line with a whip as it twisted around one of the creature's legs. Using it for leverage, he yanked back on the same one he had once damaged, causing the Heartless to fall down on one knee, and quickly scrambled up its backside, ending up on its back. Twitching his wrist once more, he turned the whip back to a sword formation, and twisted it in one hand, turning it blade down as he grasped the fur of this creature and stabbed straight down, hitting the point where the humanoid portion met the equine one.
The hunter was damaged, but his pride was more at issue than his body at present. Furthermore, he was not happy with having made such a mistake as to think this creature had blood of its own.
(Up to you if this was all enough to kill it. And how much, if any, of this fight David actually saw.)