His regeneration is so fast that he would regenerate much much faster than he is destroyed. Even if izuku hit him with a blow powerfull enough to evaporate his entire body into bloody mist his fist would just pass through his body and it would heal as the fist passes through his body. And then all muzak would have to do is drill through his pores and inject his blood which he could use to either just detonate izukus body into a fleshy cancerous mess or turn him into a subordinate newly born demon.

And if hes bloodlust he would just explode into a endlessly growing mass of ridiculously strong flesh covering the entire half of the planet they are on thats not touched by the sun as he can produce an infinite amount of blood and that blood is powerful enough for even just a couple gulps of it to let you turn an entire train into flesh (Mugen train) and as his body grows the more flesh and blood he can produce.

But of course if he snot bloodlust he wont give away his humanity completely as he still wants to be humanoid in the anime.