>>96396890
The Forge of souls is routinely used to build daemons new mechanical bodies, thats literally the bread and butter of Vashtorrs soul contracts. You give him X amount of souls and he turns you into a kick ass cyber daemon.

Perts body and soul were wounded by Fulgrim during the attempted demonic sacrifice in angel exterminatus and the Primarchs are basically already daemons piloting custom made meat mecha. There are a lot of extenuating circumstances at play here.

Besides cyber daemon Perturabo sounds pretty cool.