The Thing/ The Parasite Killer Concept.
While The Thing/ The Parasite is in its Parasite Form each time a survivor is hit; The Parasite gains 3 tokens of [Genetic Material] and 3 stacks of [Parasitic Cells] are applied to the survivor hit. Also, if The Parasite hooks a survivor or damages a generator apply 3 stacks of [Parasitic Cells] to them, [Parasitic Cells] can only be detected and removed by visiting a campfire. The more stacks of [Parasitic Cells] the survivor has the longer it takes to purge the parasitic cells gone. Survivors infected with [Parasitic Cells] apply 3 stacks of [Parasitic Cells] to other survivors, totems, hooks, generators, lockers, chests and the gate switch they interact with. When a survivor interacts with anything that has stacks of [Parasitic Cells] and is already infected with [Parasitic Cells] on them remove 2 stacks from it and is applied to the survivor instead.
When The Parasite has at least 2 tokens of [Genetic Material]. Shapeshift can be activated allowing The Parasite to transform into any survivor.
While in survivor form The Parasite can interact with generators appearing to fix it to other survivors but instead causing them to regress with skill checks that cause the gen to regress further by %. While in Survivor form when the parasite interacts with hooks, totems, gens, survivors or the switch apply 3 stacks of [Parasitic Cells]. When in survivor form you can interact with injured survivors infected with [Parasitic Cells] if you do gain 5 stacks of [Assimilated Cells] for every 3 stacks [Parasitic Cells] initially and after every 10 stacks.
When The Parasite hits a survivor infected with [Parasitic Cells] The Parasite gains 5 stacks of [Assimilated Cells] for every 5 stacks of [Parasitic Cells]. Once The Parasite reaches 50/100 stacks The Parasite can Mori a survivor in full health state.
(The Parasite changes to Survivor form after Mori)
Post your addon and perk ideas and yes, I'm aware that comms can be a problem for this idea because people can just roll call.