Cheapest priced copy (Modern Horizons 3): $0.49 at Card Kingdom, near mint, their price list as of .
Genku, Future Shaper 
Legendary Creature — Moonfolk Wizard · 2/5 · Rare · Modern Horizons 3 · #186
Whenever another nontoken permanent you control leaves the battlefield, choose one that hasn't been chosen this turn. Create a creature token with those characteristics.
• 2/2 white Fox with vigilance.
• 1/2 blue Moonfolk with flying.
• 1/1 black Rat with lifelink.
{3}{W}{U}: Put a +1/+1 counter on each creature you control.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
4 printings · $0.49 to $1.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 3 | 186 | Rare | $0.49 | $0.49 |
| Modern Horizons 3 | 373 | Rare | $0.49 | $0.79 |
| Modern Horizons 3 | 487 | Rare | — | — |
| Modern Horizons 3 Promos | 186s | Rare | — | $1.29 |
4 rulings from Wizards of the Coast
- 7 June 2024If Genku and one or more other nontoken permanents you control leave the battlefield at the same time, Genku's ability will trigger for each of those other nontoken permanents.
- 7 June 2024If multiple other nontoken permanents you control leave the battlefield simultaneously, you must still choose different modes for each instance of the triggered ability that's put onto the stack. If more than three other nontoken permanents you control leave the battlefield simultaneously, that choice is made only for the first three.
- 7 June 2024If you can't legally choose a mode because all three have been chosen that turn, that instance of the ability is removed from the stack with no effect.
- 7 June 2024If you somehow control two or more Genku, Future Shapers, track which modes have been chosen each turn for each one's ability separately.