Cheapest priced copy (Strixhaven: School of Mages Promos): $1.29 at Card Kingdom, near mint, their price list as of .
Mavinda, Students' Advocate 
Legendary Creature — Bird Advisor · 2/3 · Mythic · Strixhaven: School of Mages · #21
Flying
{0}: You may cast target instant or sorcery card from your graveyard this turn. If that spell doesn't target a creature you control, it costs {8} more to cast this way. If that spell would be put into your graveyard, exile it instead. Activate only once each turn. (You still pay the spell's costs. Timing rules for the spell still apply.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.99 to $3.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Strixhaven: School of Mages Promos | 21p | Mythic | $1.29 | $0.99 |
| Strixhaven: School of Mages Promos | 21s | Mythic | — | $3.99 |
| Strixhaven: School of Mages | 21 | Mythic | $1.29 | $0.99 |
| Strixhaven: School of Mages | 291 | Mythic | $2.49 | $2.99 |