Broodbirth Viper [Commander 2015] Kor Cleric X is the mana value

X is the mana value of that card

Set: Apocalypse Type: Enchantment Rarity: Rare Cost: {1}{B}{G} {X}

Set: Worldwake Type: Creature — Angel Rarity: Mythic Cost: {3}{W}{W}{W} Flying

"At the outset

Set: Invasion Type: Legendary Creature — Human Wizard Rarity: Rare Cost: {2}{U}{U} {1}{U}: Target spell or permanent becomes the color of your choice until end of turn

Broodbirth Viper [Commander 2015] Kor Cleric X is the mana valueSet: Commander 2015 Type: Creature Snake Rarity: Uncommon Cost: {4}{U} Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token that's a copy of this creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.) Whenever Broodbirth Viper deals combat damage to a player, you may draw a card.