It seems to me that having heads as a rare drop item is rather dull. Firstly, we've already seen rare drop items. Secondly, this would give the player plenty of useless decoration blocks filling their inventory when wandering around, without giving the player any way of accelerating the process if they actually want to make an awesome skull-filled fortress.
I think that mob heads should only drop when the mod has been killed by suffocation (or perhaps only by suffocation in sand, to make wither skulls harder to collect). I think of this as a sort of [admittedly instantaneous] "fossilization" of the mob in sand. This could either provide a definite drop of one head, or just a chance drop (which would, again, make wither skulls rightfully harder to get).
On a side note, I think that skeletons should be constructible by using a skeleton head with either iron blocks or (preferably) bone blocks, which should totally exist. This could apply to other mobs as well. These constructed mobs would not despawn. (Perhaps they could also act as utility mobs by not attacking their constructor.)
I think the main idea is that they're prize blocks, like the dragon egg only smaller and less show-offy. The secondary use for them is decoration, which in my opinion, should be more end-game; so once you have gotten to the point where you don't need to survive any more, you can place all the heads you've collected over your time in your giant fortress. The tertiary use is for the Whither, but that's supposed to be hard to get.
I think that mob heads should only drop when the mod has been killed by suffocation (or perhaps only by suffocation in sand, to make wither skulls harder to collect). I think of this as a sort of [admittedly instantaneous] "fossilization" of the mob in sand. This could either provide a definite drop of one head, or just a chance drop (which would, again, make wither skulls rightfully harder to get).
On a side note, I think that skeletons should be constructible by using a skeleton head with either iron blocks or (preferably) bone blocks, which should totally exist.
But yeah. I do like this idea, but it's a bit hard to do. They should also remain rare drops, but drop 100% of the time when suffocated.
If they dropped every time you suffocated a monster, then that would make it being a rare drop pointless.
P.S. I strongly support your bone block idea.
[quote=Badgerz]You have to keep in mind that people are stupid.
[quote=Catelite]Just because you don't understand how something works, doesn't make it broken or pointless. >_<
FOSSILS YAY +1