Zefrasaber, Swordmaster of the Nekroz
[ Pendulum Effect ] 
You cannot Pendulum Summon monsters, except "Nekroz" and "Zefra" monsters. This effect cannot be negated.
[ Monster Effect ] 
You can Tribute this card from your hand or face-up from your side of the field; Tribute monsters from your hand or field, then Ritual Summon 1 "Nekroz" Ritual Monster from your hand whose Level exactly equals the total Levels of those monsters. You can only use this effect of "Zefrasaber, Swordmaster of the Nekroz" once per turn.