what you already know about tombstones: 1. a placed tombstone can't do damage, but what about one that has been mid dropped, would it be useful for defeating eye of Cthulhu? would a tombstone that had been on purposely dropped by the player do the foggiest bit of damage? you can find out, by experimenting, but i would be wise to test out these theories first, talk about the tombstone a little and how it helped you(such as conserving wood)
I feel tombstones should do a LOT more damage after you die. At the very least kill whatever killed you. Revenge by tombstone.