Dyraxe's unliving armor

You touch a skeleton or zombie under your control, forcing its body to wrap around you, creating a defensive exoskeleton of flesh and bone. The exoskeleton keeps the stats of the undead used to create it. Whenever you're hit by an attack while wearing this armor it takes damage instead of you. The spell ends whenever the armor is destroyed. You can don this armor by spending an action, the undead used to create it regains its previous form as a result. If the time you can control the undead used to form the armor runs out while this spell is still active it runs out immediately after this spell ends instead. This kind of armor does not impose any disadvantages regarding spellcasting.

This armor can receive commands the same way as a skeleton or zombie would, but it can't act at the same turn as its wearer. Its initiative is immediately after its master. Armor's movement is halved and it has a disadvantage on all skill checks due to the creature's altered physique.

The additional benefits granted by the spell depend on the type of undead used. 

Skeleton. Your AC becomes 14 + your Dex modifier (max 2). Skeleton loses vulnerability to bludgeoning damage while in this form.

Zombie.  You gain resistance to poison. Regardless if the zombie passes the Undead Fortitude check or not the remaining damage of the attack that triggered the check does not damage you.

At higher levels. When cast using a 5th level spell slot or higher you can target up to 4 medium-sized undead creatures of the same type adjacent to each other or one Large. As a result, the armor gains the combined HP of the creatures targeted and your size becomes Large. Undead-type specific bonuses also increase.

Skeleton. Your AC becomes 16 + your Dex modifier (max 2). And your movement speed increases by 10ft.

Zombie. You add your proficiency modifier to Undead Fortitude checks of this armor. You gain an advantage on athletics checks and Str saving throws.