Quartz Golem

A Quartz Golem is a village's form of witch. It throws potions at mobs to kill them, generally alongside Iron Golems to protect the village. They can be used to create a quartz farm. 

A Quartz Golem can be created by placing four blocks of quartz together in a 'T' shape with a carved pumpkin on top, much like an Iron Golem. However, in order to activate the Golem, you must throw a splash or lingering potion on it. This will decide what potion the Golem will throw. Naturally spawning Quartz Golems will throw splash potions of healing to combat the undead and keep villagers alive. Note that natural Quartz Golems are rarer than Iron Golems. Quartz Golems will only target hostile mobs with potions that can harm them. While they can throw potions like speed and leaping, they won't throw them except at villagers.

Quartz Golems only throw ONE type of potion, so you'll need one with harming and one with healing to kill most mob types.

All is subject to change and none is set in stone. If Microsoft sees this, feel free to change as many aspects as you want.