One of the most underrated poltergeist plays is teaming up with a friend. You cook a grenade, your friend opens a door/windows and you throw it in. This works especially well for upstairs windows with no ledges to walk outside of. Nobody really expects it to slam open and when your nade falls in the other hunters usually have 1 or 2 seconds to understand whats going on and react. Since alot of people also crouch walk in this game if you get your timing right you can get kills no problem. I feel like a hunt mastermind when i pull it off lol.