Cheapest priced copy (Wilds of Eldraine): $1.49 at Card Kingdom, near mint, their price list as of .
Will, Scion of Peace 
Legendary Creature — Human Wizard · 2/4 · Mythic · Wilds of Eldraine Promos · #218p
Vigilance
{T}: Spells you cast this turn that are white and/or blue cost {X} less to cast, where X is the amount of life you gained this turn. Activate only as a sorcery.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
4 printings · $1.49 to $4.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Wilds of Eldraine Promos | 218p | Mythic | $3.99 | $4.49 |
| Wilds of Eldraine Promos | 218s | Mythic | — | $2.99 |
| Wilds of Eldraine | 218 | Mythic | $1.49 | $1.49 |
| Wilds of Eldraine | 302 | Mythic | $1.99 | $4.99 |
4 rulings from Wizards of the Coast
- 1 September 2023Will's activated ability can't reduce the amount of colored mana you pay for a spell. It reduces only the generic mana component of that cost.
- 1 September 2023Will's activated ability counts the total amount of life you gained without taking into account any life you lost during that turn. For example, if you gained 3 life and lost 3 life earlier in the turn, the cost of white and/or blue spells you cast this turn will be reduced by {3}.
- 1 September 2023The value of X is determined only once, at the time Will, Scion of Peace's activated ability resolves.
- 1 September 2023Will's activated ability doesn't change the mana cost or mana value of any spell. It changes only the total cost you pay.