I just learned that approach velocity works CONSTANTLY with Yuumi.

I'm unsure if it's intended, but Approach Velocity, which grants 15% movement speed towards movement impaired allies, applies to Yuumi, whenever she is attached to someone—including yourself. This effectively granted me +53 movement speed as Rakan whenever Yuumi was attached to me, granting more movement speed than most T2 boots. Additionally, in a 21:20 ARAM game, this wound up granting me 392 seconds (6 minutes, 32 seconds) worth of movement bonuses. Honestly, this could be a really strong interaction, especially for someone like Ezreal who already takes the Inspiration tree as his primary.