Ok, I just randomly came up with this idea so here it goes.
The Player Decoy item would be found in end city’s, with the ability to copy the appearance of your player character. This confuses mobs and they will attack your decoy instead of you. The decoy will follow you and take the same amount of damage that an iron golem can. Once your decoy has taken up all of its hearts, it will break. The only way to fix the decoy will be to put it in a crafting table with a golden Apple, and you can use it again, and again, as long as you have golden apples to repair it.