Mordekaiser Lore Speculation
Beneath his armor he is made of bugs.... but like, literally.
https://ohmy.disney.com/wp-content/uploads/sites/25/2014/09/Oogie-Boogie-Scariest-Nightmare-Bugs.gif
So, instead of causing metal to swarm around him and his target, it will be bugs, and instead of controlling spirits, he reanimates their bodies... by filling them with bugs.
