Neeko Can't Use Skills or Autos
I used Neeko's passive to turn into our jungle and engaged a fight with twin shadows, R, and flash. As soon as I landed from my ult, I was back to looking like Neeko, but I had no portrait, was a white square on the mini-map, no skills other than W were available, I had no mana bar, and I couldn't auto-attack.
Dying to an enemy allowed me to use my passive again, and which point all functionality returned. This however cost us the game as I wasn't a champion for several minutes.