Armed Dragon Lv7 [SD1-ENDE1] Secret Rare Mirrodin Promos this card cannot be selected

this card cannot be selected as an attack target

Set: Core Set 2021 Prerelease Promos Type: Enchantment Rarity: Rare Cost: {1}{W}{W} Hexproof

but how do we get down

Set: Dragons of Tarkir Prerelease Promos Type: Legendary Creature — Zombie Naga Rarity: Rare Cost: {3}{B}{B} Deathtouch

Check all monster on your opponent's side of the field

Armed Dragon Lv7 [SD1-ENDE1] Secret Rare Mirrodin Promos this card cannot be selectedSet: Structure Deck: Deluxe Edition Card type: Effect Monster Rarity: Secret Rare Attack: 2800 Defense: 1000 This card cannot be Normal Summoned or Set. This card cannot be Special Summoned except by the effect of "Armed Dragon LV5". Send 1 monster card from your hand to the Graveyard to destroy all face up monsters on your opponent's side of the field with an ATK equal to or less than the ATK of the sent monster.