Imma go with Monsterization since it have a lot of varieties

As with Demons as well (Elemental Demons, Yokai, Demonic Dragons, Alpha Demons, Hellspawns, Ascended Demons etc.)

Second option

But every demon is a monster but not every monster is a demon. plus term monster is more broad then demon. i can turn someone into monster who see the future but turn back into human if heard bad dad joke.