Cheapest priced copy (Outlaws of Thunder Junction Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Kaza, Roil Chaser 
Legendary Creature — Human Wizard · 1/2 · Rare · Zendikar Rising · #367
Flying, haste
{T}: The next instant or sorcery spell you cast this turn costs {X} less to cast, where X is the number of Wizards you control as this ability resolves.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
5 printings · $0.49 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Outlaws of Thunder Junction Commander | 232 | Rare | $0.49 | — |
| Zendikar Rising Promos | 225p | Rare | $0.49 | $2.99 |
| Zendikar Rising Promos | 225s | Rare | — | $2.49 |
| Zendikar Rising | 225 | Rare | $0.49 | $0.79 |
| Zendikar Rising | 367 | Rare | $0.49 | $0.99 |
2 rulings from Wizards of the Coast
- 25 September 2020To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Kaza's activated ability). The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.
- 25 September 2020Kaza's cost reduction can reduce only generic mana in a spell's cost. It can't reduce colored mana requirements.