I'm actually wondering the same thing tbh, because in canon Viktor has been given abilities that can probably be answered simply with ‘magic’. How does he manage to turn human bodies into machines? We see during the transformation that he randomly takes metal parts from the environment (?). But in the end, they merge with the body in a very visually appealing way.

The dolls at the end also all look pretty much the same - so he must have some kind of ability to turn flesh into metal. That made me think and come to the conclusion that he can probably influence materials as a mage now.

In my head, after his journey through the Arcane, he's fused with the rune that gives him the same abilities as the hexcore, just without the corruption. Which means he can still influence... bodies? Materials?

So I guess his body is real, infused with the Arcane (with its many scars), but he can mould environments to his liking. Like, he can also change Jayce's clothes. Pulverise, so to speak. Maybe reabsorb it as magical energy. Perhaps he can also conjure up clothes?

That all depends a bit on what abilities he has canon-wise. But as I understand it… Viktor can change materials 🙃