I searched for "Bandit Camp" via site search and didn't hit anything related to possession, so here comes a nice little thing I stumbled upon.
If there is possession on the board and it's likely to be an engine mirror, a Bandit Camp is a very good choice of pieces you want to add to your deck. Why is that?
1. It is an important engine piece in that it provides +action.
2. It provides $. So even if you trashed all your money, so that your opponent cannot use it while possessing you, you still have some $ to use.
3. It provides $ - only for you. This holds if you can draw your deck reliably and are playing possession reliably every turn. In your turn, you'll draw spoils the same turn you played BC. On possessed turns, your opponent gains Spoils himself so he cannot use it immediately. Moreover, you can use it when you possess him since he didn't have time to use it between adding it to his deck and being subjected to your possession.
Here is a
sample game, where poor yed suffered from exactly this for several turns.