Oathbreaker

Oathbreaker (オースブレーカ Ōsuburēka) in Japanese is a set of 6 monsters, 1 of each Attribute, created by LHK. They are said to be the evolutions of the "" monsters used by, save and , as they have 2 Levels higher and 500 ATK and DEF higher than their Guardians. All "Oathbreakers" are Special Summon Monsters and all of them, save "Oathbreaker Elma, the Fairy with the Swift Sword", have these effects:

"Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand) by banishing 1 *Equip Spell Card that must be on the field to Summon the /basic/ Guardian* from your Graveyard OR sending 1 *counterpart Guardian* you control equipped with an Equip Spell Card to the Graveyard, and cannot be Special Summoned by other ways. [...] If this card is destroyed by battle and sent to the Graveyard: You can target 1 *counterpart Guardian* in your Graveyard; add that target to your hand."