Amazing work! I wish I could draw like that.
If I could make a small bit of constructive criticism... Mordekaiser seems a bit slender here. I understand if you wanted to take away the cartoonishly big armor pieces he has now, but I think he should be bulkier and look like an unshakable giant even if you don't have a point of reference for his (40 feet?) height.
Additionally, as somebody who has rigorously studied the effects of cloth and how it drapes (I love capes, f*ck you Edna), I think your cape seems a bit cartoon-like and almost excessively heroic. I think the cape should drape down a bit around his shoulders and create a bit of a cloak effect behind him so that his silhouette is more enveloping and intimidating. I know this is a rough sketch, but this is just my input because you've inspired my creative juices.
Besides those two little things, again, awesome work. I envy your talent.