[Azinctus]

I've been using a houserule for burning HP to cast spells in my DF campaign and I'd like to see what people think of it.

When a PC burns FP they don't suffer a -1 to the spell per HP used. However you can't use HP until you are at zero Fatigue. There is no special protection against death. You cast the spell, mark off the HP and then make any health rolls. If you die, you die.

I found that PCs never use HP because the malus is too severe, the PC would like to risk his life for one last spell but because of the malus the spell has too low a chance of working anyway.

What do you think? Is this open to too much munchkingly abuse? Could I modify it to get the same results but close out some of the abusive uses? (I think there might be an exploit with Lend Energy/Major Healing where a party could profit from this rule)