Mutavault [Morningtide] Core Set 2019 Prerelease Promos the player can activate mana

the player can activate mana abilities only if they're from lands that player controls and only if mana they produce is spent to activate other mana abilities of lands the player controls and/or to play that card

Add an amount of mana of that color equal to your devotion to that color

" —Sarnvax

Upon his return to the capitol after taking soldiers to loot a nearby peaceful town

Mutavault [Morningtide] Core Set 2019 Prerelease Promos the player can activate manaSet: Morningtide Type: Land Rare Cost: {T}: Add {C}. {1}: Mutavault becomes a 2 2 creature with all creature types until end of turn. It's still a land. Some changelings born at Velis Vel never return, but their essence never leaves.