Token Of Undead

 You will be able to can craft a worse version of Totem of Undying, out of emeralds, iron blocks and lapiz, or can be found like craftable golden apples. Instead of not letting you die, this Totem of Undying will transform its user into an undead mob, like a skeleton, a zombie, stray or husk.

 Health left will be only half a heart, plus no buffs like normal totem gives. Instead, you will get DEBUFFS like less max health points if you are a skeleton, endless hunger effect lvl1 if you are a zombie, endless slowness if you are a stray or hunger lvl2 if you are a husk. Also, you WILL be burned in the sun without a helmet, and the only bonus it will give is that every mob that is the one you transformed into won't attack you. If you are a zombie, skeletons will attack you, and other zombies will ignore you.

 Perhaps, a gamerule can be added for the worse Totems of Undying to act like the normal, and a special "Undead" effect (that has endless duration and can't be cured with milk (hopefully healing 100% every effect with milk will be fixed), but when given with commands can be timed), that transforms the player into any undead mob.

 Crafting: putting iron blocks like sand in TNT crafting recepe, in the center - lapiz, on the corners - emeralds (or maybe diamonds)