Einherjar

Einherjars (死せる勇者の魂) are magic constructs that can be summoned through a skill originating from YGGDRASIL.

Background
Einherjars are magically created golem-like constructs. Once the skill is activated, a ball of white light coalesces in front of the summoner, which slowly shapes itself into a humanoid form until fully resolving itself into the shape of a person.

Appearance
Einherjars are considered physical bleached-white replicas of their summoners.

Abilities
Einherjars, though a cosmetic reflection of their creators lacks spellcasting abilities and several skills. While possessing no magic items, they are able to mimic their summoner's overall appearance of weapons, armor, etc. The stats of these beings were otherwise the same as the user who summoned it. As golem-like constructs, they nearly had identical resistances and immunities like the undead.

Trivia

 * Shalltear Bloodfallen is able to summon an Einherjar and use it as her trump card as shown during her battle with Ainz Ooal Gown in Light Novel Volume 3.
 * In Norse mythology, Einherjars are warriors who have died in battle and are brought to Valhalla by valkyries.