
This comboes extremely well with Blood Pact and Sin-Eater. It is 9 xp, but for that you get pretty much inexhaustible Guts/Overpower on demand:
- 2 charges to start with
- recharge the mask with one use of Blood Pact (and gain +3 from there)
- after the mask is again empty, move the doom to Sin-Eater, the mask refills again. You do have to occasionally use an action to empty the doom (and while there is doom in there, moving another doom doesn't fill the mask), but it's extremely action and resource efficient.