Another class!
Name: Infiltrator
This class is a class that is very much like Spy from TF2. This class uses a silences revolver (Suppressed .44 Magnum Colt Anaconda), a knife, EMP grenade (instead of Electro-Sapper) which disables enemy buildings and vehicles, and a Shock grenade or a Flashbang.
Since this class has the ability to cloak and move relatively fast, it should have relatively lower health than most classes.
(Also, if you are willing to do you could try to make a disguise kit where you can disguise with the enemies' team color instead of just being blue and red like the ones we have now.)
This class can also do headshots while in close-range and can backstab enemies dealing them 70% ~ 100% damage.
Also for cloaking, it should be like TF2's cloak and dagger meaning that if you don't move, the cloak meter doesn't decrease. But it doesn't increase while cloaking to make it a little bit more fair. When the player moves fast, cloak meter decreases faster. So if you want to save the cloak meter and still move, it's better to crawl than move.
And just like in TF2, if the minigame resets or the player dies, the cloak meter is refilled to 100%.
While cloaking, if the player bumps with the enemy or stay really close to the enemy, the enemy should be able to see the Infiltrator. Also when the Infiltrator gets on fire, he's good as dead unless he gets away from the enemies and hide somewhere safe and wait for the fire to extinguish. Also, be sure not to jump into a pool of water because the enemy will see the water splashing and might get suspicious.
This class should be strong against snipers, trappers, engineers, combat medics, and officers/communicators, but weak against firebugs, demolitions, and maybe berserkers.
Again, no catchphrases...
And here's a suggestion on how Infiltrator should look like.

Still no tablet :(
EDIT: You could still make it use an invisibility watch or you could come up with something.