Maoki and Anivia Glitch: Becoming a True Tree (On ARAM? Or Everywhere?) [Gameplay]

So this happened on ARAM today. I was playing Anivia (purple team), and there was a Maoki on the other team (blue team). Unfortunately, I could not get a screenshot, but here is how it went. My team had destroyed all of the other teams towers. Right after we destroyed the enemy inhib, Maoki began chasing me (Anivia). As soon as we got to the rubble/impassable terrain of the blue teams second turret, Maoki used his W to jump to me. As he was mid W, I used my W, the wall, to try and stop him. We were right below of the blue team's turret right before their inhib. Anyway, as soon as I cast my wall, Maoki become part of the map. His health bar and character kind of greyed out, and he became invincible and unable to move. He was still able to cast his Q, E and R, just not his W or Flash. You could not target him with abilities or anything; essentially, he became part of the map itself. A true tree. TL;DR; Anivia can make Maoki part of the map with her wall as he uses his W on her. Not sure if this only occurs on ARAM, or on other maps too.

Thanks,

Swuft