Spy now has a brand-new tank! It doesn't fire anything, but it has the plague ability from Mannpower mode when the player is above 200 HP.
The other feature of the spy tank is that it can turn invisible! It's bound to the player's normal cloak/decloak button, and uses their normal cloak meter. Note that this is not complete invisibility, as the particle effects from the plague ability will still show up. Still, it's useful when trying to get near enough to enemies that you can infect them!
Additionally, Demoman's tank now has 45% damage resistance against ranged attacks, and Heavy's tank now has 45% damage resistance when above 2000 HP.
Spy tank bugs:
There's currently a bug where insta-death will cause the powerup to drop, so fixing that's first on my to-do list.
Cloaking with the spy tank screws up the color of the model, making it really dark.