Insult // Injury [Amonkhet Prerelease Promos] Nightmare the ATK of the equipped

the ATK of the equipped monster becomes double the equipped monster's original ATK

You must also Tribute monsters from your hand or field whose total Levels equal or exceed the Level of the Ritual Monster you Ritual Summon

Set: Modern Masters 2015 Type: Creature — Snake Rarity: Uncommon Cost: {1}{G}{U} Whenever you draw a card

then if you control "Exosister Stella"

Insult // Injury [Amonkhet Prerelease Promos] Nightmare the ATK of the equippedSet: Amonkhet Prerelease Promos Type: Sorcery Sorcery Rarity: Rare Cost: {2}{R} {2}{R} Damage can't be prevented this turn. If a source you control would deal damage this turn, it deals double that damage instead. Reverse Type: Sorcery Aftermath (Cast this spell only from your graveyard. Then exile it.) Injury deals 2 damage to target creature and 2 damage to target player or planeswalker.