User blog comment:KaiserLos24/My Champion Concepts: Legion, the Dread Symbiote/@comment-5266525-20130801125214

That passive is the better half of Rengar's ultimate without any restricting cooldowns. I'm pretty sure it's overpowered unless the range is obscenely small.

The rest of his kit and lore appears somewhat uninspired to me. His ult is basically just a Zilean Time Bomb with an attached DoT and healing component.