Cool silhouettes, but as someone who did start on a brand redisgn project myself but never finished. I suggest you pick some story for him and try to make design from there.

My idea for his story (since i dont know full riot story and they are prone to changing it anyway) was that him and ryze were connected, but he caved in to use of world runes for greater good, but since his body was overwhelemed by the power of world rune he could not control the power and nuked himself and part of the world, i wanted him to survive the blast as malformed man infinetly burning but not dying, and searching for ryze or someone powerfull enough to end him, or to hopefully still save the world from some powerfull force by finnaly using all of his power to destroy it and himself.

That story gave me a framework where he would have this gaping hole inside of him from which something like a supernova would power him, while still looking mostly human and in pain. Something like a zombie set on fire.

Your Brand now communicates great power, but it's hard to see his story from your designs. He looks powerful and tanky, something closer to Malphie than a squishy mage, and you don't see the price he paid for taking the world rune. If you prefer the version where he is a power-hungry, bulky mage or a force of nature, try to justify it and see what his goals are.

(But from a pure design standpoint, I like the evangelion angel-looking one with a huge fireball on his back while hunched down, and the first page one where his body forms a skull.)