Cheapest priced copy (Ikoria: Lair of Behemoths): $0.35 at Card Kingdom, near mint, their price list as of .
Huntmaster Liger 
Creature — Cat · 3/4 · Uncommon · Ikoria: Lair of Behemoths · #16
Mutate {2}{W} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Whenever this creature mutates, other creatures you control get +X/+X until end of turn, where X is the number of times this creature has mutated.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ikoria: Lair of Behemoths | 16 | Uncommon | $0.35 | $0.49 |
| Ikoria: Lair of Behemoths | 280 | Uncommon | $0.35 | $0.49 |
| Ikoria: Lair of Behemoths (King Caesar, Ancient Guardian) | 370 | Uncommon | $0.69 | $0.79 |
2 rulings from Wizards of the Coast
- 17 April 2020The value of X is determined only as the triggered ability resolves. Once that happens, the value of X won’t change later in the turn even if Huntmaster Liger mutates again, although in that case the creatures will receive a second, larger +X/+X in addition to the one generated by the ability’s earlier resolution.
- 17 April 2020Huntmaster Liger’s triggered ability affects only creatures you control at the time it resolves. Creatures you begin to control later in the turn won’t get +X/+X.