Redcap

Redcaps are a variant of goblins from YGGDRASIL that can be summoned through either using a Horn of the Goblin General under specific conditions or a special book found in Nazarick's library Ashurbanipal.

Appearance
Redcaps are described as evil and twisted looking goblins. Barring weapon difference aside, every Redcap variant seems to commonly wear a pointed red hat and steel boots.

Abilities
Redcaps have the ability to hide within their summoner's shadow and possibly their target too for that matter. At the same time, they can even go as far as reemerging out of that person's shadow if ordered to and then carry out their surprise attack.

A Redcap's primary weapon in battle seems to vary among its summoners. For starters, while the ones summoned by Enri wielded long scythes, the ones summoned by Lupusregina were equipped with axes instead.

According to Maruyama, since the Redcaps usually fight together as a unit especially in Enri's Goblin Army, it is impossible to exploit their weakness.

Trivia

 * A Redcap in English folklore is a malevolent, murderous goblin that is said to inhabit ruined castles especially where there were once the scenes of tyranny or wicked deeds, and is known for soaking its cap in the blood of its victims.
 * Enri has thirteen of these beings as a division called Goblin Bodyguards serving under her leadership in the Goblin Army.
 * Lupusregina conjured thirty Redcaps that were estimated to be level 43. She also heavily hinted on the fact that these Redcaps are the lowest-leveled goblins summonable in Nazarick's library.
 * According to Maruyama Tweet, Enri's Redcaps are estimated to be at the same level as Lupusregina’s Redcaps.
 * Redcap's ability seems to be exactly similar to that of the Shadow Demon's ability.