Cheapest priced copy (Bloomburrow): $0.69 at Card Kingdom, near mint, their price list as of .
Stormcatch Mentor 
Creature — Otter Wizard · 1/1 · Uncommon · Bloomburrow · #385
Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Instant and sorcery spells you cast cost {1} less to cast.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
4 printings · $0.69 to $5.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Bloomburrow | 234 | Uncommon | $0.69 | $1.99 |
| Bloomburrow | 385 | Uncommon | $2.49 | $5.99 |
| The List | BLB-234 | Uncommon | — | — |
| Secrets of Strixhaven Commander | 331 | Uncommon | $0.79 | — |
2 rulings from Wizards of the Coast
- 26 July 2024The cost reduction applies only to generic mana in the total cost of instant and sorcery spells you cast.
- 26 July 2024To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as a flashback cost), add any cost increases (such as kicker costs), then apply any cost reductions (such as that of this ability). The mana value of the spell is determined by only its mana cost, no matter what the total cost to cast that spell was.