Unlimited Mana:
Find the Heaven & hell savegame folder and open the MissionData.save file using notepad.

If you are playing on the Heaven (good) side then look for BaseSate = hbsGood

If playing on the Hell (Bad) side then look for BaseState = hbsBad and look for the line that says:

EnergyCount:
Now change the number you find there to a large number to give you unlimited mana