Cheapest priced copy (Commander Masters): $0.59 at Card Kingdom, near mint, their price list as of .
Hamza, Guardian of Arashin 
Legendary Creature — Elephant Warrior · 5/5 · Uncommon · Commander Masters · #339
This spell costs {1} less to cast for each creature you control with a +1/+1 counter on it.
Creature spells you cast cost {1} less to cast for each creature you control with a +1/+1 counter on it.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
4 printings · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 339 | Uncommon | $0.59 | $0.49 |
| Commander Legends | 278 | Uncommon | $0.59 | $0.79 |
| Commander Legends | 598 | Uncommon | — | — |
| March of the Machine Commander | 327 | Uncommon | $0.59 | — |
3 rulings from Wizards of the Coast
- 10 November 2020Once you announce you're casting a creature spell, no player may take actions until the spell has been paid for. Notably, opponents can't try to change the number of creatures you control with +1/+1 counters.
- 10 November 2020Hamza's first ability affects only generic mana costs. It can't reduce the total cost to cast the spell below {G}{W}.
- 10 November 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 Hamza, Guardian of Arashin). The total cost is locked in before any costs are paid. The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.