You can Ritual Summon this card with "Nightmare Clad Ritual". Cannot be destroyed by battle. This card's original ATK/DEF are equal to the difference between your Life Points and your opponent Life Points. This card gains the following effects, depending on the Attributes of the monster(s) used to Ritual Summon it. You can only use 1 of the following effects of "Shadow Armory" per turn, and only once during that turn.
LIGHT: When an opponent's monster declares an attack (Quick Effect), you can banish 1 LIGHT monster from your Graveyard to target the attacking monster; banish it, and if you do, gain Life Points equal to half the banished monster's ATK.
WIND: When this card battles an opponent's monster (Quick Effect), you can banish 1 WIND monster from your Graveyard; This card gains ATK equal to the battling monster's ATK until the End Phase.
WATER: You can banish 1 WATER monster from your Graveyard; destroy all Spell/Trap Cards on the field, and if you do, this card gains 500 ATK until the End Phase.
EARTH: You can banish 1 EARTH monster from your Graveyard; switch all other monsters to face-up Defense Position, and if you do, their effects are negated, also when this card battles a Defense Position monster, inflict piercing battle damage.
FIRE: If your opponent's Life Points are equal to your Life Points, you can banish 1 FIRE monster from your Graveyard; your opponent's Life Points are halved, also double your Life Points. This card cannot declare an attack the turn you activate this effect.