Soul Shards Mod 1.6.4

Soul Shards allows you to create a Soul Shard that absorbs the souls of monsters you kill to be inserted into a Soul Cage later. This Soul Cage is a special block that can spawn the type of mob your Soul Shard was absorbing, usually at much better rates than a vanilla monster spawner.

This mod’s cages can sometimes spawn monsters you can’t normally get with vanilla spawners. In addition high tier shards can spawn special monsters and have other bonuses.

Download: http://www.5minecraft.net/soul-shards-mod/