Basically, it would be like the Flood in Halo.

Trap: When the trap is triggered a few bugs or parasites would pop out and infect enemy troops. It would only be able to infect weaker troops so it wouldn't be completely OP. It would be invincible while infecting its host so that it won't die and not do anything useful.

Dark Troop: It would be like the trap as mentioned above. There would be some bugs or parasites that could attach to CC troops and make them your own. Not anything like a Pekka or something, only weaker troops. Maybe even infect the enemy's heroes for a few seconds. It could also infect archers on archer towers or the wizards on wizard towers and turn them on their own base. Or another troop idea is that it would be an engineer or a mechanic who would be able to make cannons, mortars, air defenses, hidden Teslas help you. Anything that doesn't have something alive on it.

Stats: I'm not sure what All the stats would be yet.