Sanguine Spy

{2}{B}Creature — Vampire Rogue2/3

Menace, lifelink

{1}, Sacrifice another creature: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

At the beginning of your end step, if there are five or more mana values among cards in your graveyard, you may pay 2 life. If you do, draw a card.

Lifelink. Damage dealt by this also causes its controller to gain that much life. · CR 702.15

Menace. This creature can't be blocked except by two or more creatures. · CR 702.111

The mana value of a double-faced card in your graveyard is always the mana value of the front face. (2022-04-29)
X is 0 when determining the mana value of a card in your graveyard. (2022-04-29)
“Five or more mana values among cards in your graveyard” means there are at least five different mana values among those cards. (2022-04-29)
Sanguine Spy's triggered ability checks the number of mana values among cards you control both when the ability triggers and when it resolves. If you no longer have five or more mana values among those cards when the ability resolves, you may not pay 2 life. (2022-04-29)
The mana value of a split card in the graveyard is the total mana value of both halves of that card. It does not have two mana values. (2022-04-29)
The mana value of a land card is 0. (2022-04-29)