You can only control 1 "Nidhogg, Generaider Boss of Ice". When your opponent would Special Summon a monster(s) (Quick Effect): You can Tribute 1 "Generaider" monster or 1 Wyrm monster; negate the Summon, and if you do, destroy that monster(s). You can only use this effect of "Nidhogg, Generaider Boss of Ice" once per turn.
