if your talking about Adventure Quest Worlds, keep fighting Bone Terror until you get it!
On AdventureQuest Worlds, Bone Mace is found in the museum. It cannot be purchased, rather it is a reward for the Monday Bone Mace Quest.
In Battleunder (/join battleundera)
call 250-505-1612
kill the skeletons at sword haven
There is no way to know the exact drop rate to anything unless your a mod but it's estimated around 1-2%
valencia in battleon. a specific day. I'm not sure which one
keep killing big black sprat i think in the grave yard
go to yulgar and then go to room 42 and Customize your skin
Battle an Undead Giant......at least that works for me
All of these items are found in the marsh, marsh2, or ruins. Hair- Dark Witch Bone- Lich Teeth- Undead Berserker
just keep killing him until you get the Undead Plague Spear, the Skeleton Hand, or the Bone Axe.