You can only control 1 "Hela, Generaider Boss of Doom". (Quick Effect): You can Tribute 1 "Generaider" monster or 1 Zombie monster, then target 1 "Generaider" monster or 1 Zombie monster in your GY, with a different name than the Tributed monster had on the field; Special Summon that monster in Defense Position. You can only use this effect of "Hela, Generaider Boss of Doom" once per turn.