Slifer the Sky Dragon [JUMP-EN061] Ultra Rare Champion Pack 1 but while this effect is

but while this effect is applied

) You can target 1 EARTH monster in your opponent's GY

You can only activate 1 "Spellbook of Power" per turn

and neither player takes damage until the end of the opponent's next turn

then you can Set 1 Spell/Trap from your Deck that mentions "Dark Magician"

Slifer the Sky Dragon [JUMP-EN061] Ultra Rare Champion Pack 1 but while this effect isSet: Shonen Jump Magazine Promos Card type: Effect Monster Rarity: Ultra Rare Attack: ? Defense: ? Requires 3 Tributes to Normal Summon (cannot be Normal Set). This card's Normal Summon cannot be negated. When Normal Summoned, cards and effects cannot be activated. During the End Phase, if this card was Special Summoned: Send it to the Graveyard. This card gains 1000 ATK and DEF for each card in your hand. When a monster(s) is Normal or Special