Talking Skulls

You touch the skull of a deceased/inanimate creature, and say a specific phrase and a triggering event. i.e. "Say 'You must flee!' whenever a goblin approaches." (This is the Verbal component of the spell.)

You can specify whether the skull should repeat the phrase or say it only once, and whether it should whisper, speak, or shout it. 

The skull has darkvision up to 30 feet and 5 feet of blindsight. You can only animate a number of skulls up to your PC level. If you animate another skull more than your level, then one of the previous skulls becomes inanimate. 

You can only cast this spell on an Undead creature if they have been reduced to zero hp. 

At level 10, you can imbue the skulls with a personality aspect. i.e. "You will greet any goblins that approach and inform them not to annoy the wizard who lives here."

At level 20, the skulls have 60 feet darkvision and 10 feet blindsight.