Ephemerate (Retro Foil Etched) [Modern Horizons] San Diego Comic-Con 2018 You may spend blue mana

You may spend blue mana as though it were mana of any color to pay the activation costs of Quicksilver Elemental's abilities

In Unquiet Dead

+1: Target artifact or creature loses all abilities and becomes a green Elk creature with base power and toughness 3/3

" —Laurence Sterne

Ephemerate (Retro Foil Etched) [Modern Horizons] San Diego Comic-Con 2018 You may spend blue manaSet: Modern Horizons Type: Instant Rarity: Uncommon Cost: {W} Exile target creature you control, then return it to the battlefield under its owner's control. Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)