Even though I know it's not him, I'm gonna explore the idea of it being Tate for a few reasons...
#1 - it's way too obvious that it's either Tasha or Tariq so Courtney might wanna shake things up
2 - Tate's character has been very underwhelming thus far. Remember when he was first introduced and we all thought he was gonna be some secret final boss type big bad? Never really happened. So they could try and set up his character to star in book 2.
3 - he's already attempted to kill Ghost twice so far (Cedric, Dre) and he always seems to know exactly where Ghost is gonna be (has had people following and watching him the whole season)
So who knows...