Hmm, after thinking for some time, I decided that the cart only remains while you hold it in at least one hand, otherwise there's just too many questions about what happens if somebody else tries to push the cart
Forbidden Cost: Whenever you fail a Will save, you lose HP equal to your current Forbidden Price. Whenever you succeed on a Will save, you lose HP equal to half your current Forbidden Price. You must also have a maneuver/stance level number of corpses from sentient creatures at hand that are consumed as part of initiating the maneuver or entering the stance, burned to ashes, or you're consumed yourself.
Anyone resting inside this mansion must make a Will save with DC 20 or go one step closer to evil. If they're already evil they must make a Will save with DC 20 or retrain their last level to Fiendish Creature.
"Vengeful Cat Spirit's Erratic Step" Evil CatWhen you initiate this boost you replicate one spell with the [Evil] descriptor as a free action with a CL equal to your ranks in Profession (Ferrymen) and DC based off your Int (if any).