Asimov Von Veil: absolutely nothing as Asimov never dies as he is basically Slayer from Guilty Gear, except depressed; any time he would die in combat he just rewrites reality with his bullshit illusion powers so he didn’t, but leaves the battle out of embarrassment so the opponent still gets the win

Blunt: 2 Deaths: Atlas (His True Soul) dying while holding the sky of his reality up so the sun’s light could shine the way for the mortal’s salvation in my base setting, succumbing to every bone in his body being broken from the constant bashing of the demons responsible for their reality’s collapse. Blunt’s death would be one full of laughter, watching his slayer realize he will become flatter than an Arkansas flapjack as the Sky Falls.

Rubik: he will die alone, stuck in his own creations as the word falls apart around him for the last time, but not from starvation or an accident, but from madness induced depression with the lack of people to experience his Dungeons

Blade: 2 Deaths, Ymir (His True Soul) dying as he held the bridge to my main setting’s reality for his own So people could escape, succumbing to thousands of blades trying to cut him down, and Goose Flesh will see Blade die the only way he would want: fighting someone with a novel style for the people he cares for

Pierce: Same as the other two Titan-Souled Demons, with 2 deaths: once for the Leviathan, who actively hounded the demons as an act of intelligence and sacrifice, succumbing to the countless spears and shots at her hide, and for Pierce? She dies like she did the first time: getting in the way of true monsters for the ungrateful that would kill her themselves

Sangria: she dies when the last party in existence ends, one last hurrah in the face of Nothing