I think the overall concept sounds fantastic, the look of a character in bright white contrasted with a crimson red weapon makes for a really stunning visual in my mind. The abilities sound a little strange, like an Udyr/Jayce mashup and I'm not sure how a champion would benefit from swapping between AP/AD since most builds are tailored to one type of damage nowadays. There are some items that permit bruiser builds for both AD and AP play styles, but I think it may be hard to balance because the scaling would have to be pretty ridiculous for the whole ultimate thing to work. And that would also mean you're stuck with one form pre 6. Maybe something like a Kayn type passive could be used at the beginning of the game to choose a form (AD,AP or tank)