Cheapest priced copy (Commander 2019): $14.99 at Card Kingdom, near mint, their price list as of .
Apex Altisaur 
Creature — Dinosaur · 10/10 · Rare · The Lost Caverns of Ixalan Commander · #232
When this creature enters, it fights up to one target creature you don't control.
Enrage — Whenever this creature is dealt damage, it fights up to one target creature you don't control.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $14.99 to $16.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2019 | 31 | Rare | $14.99 | — |
| The Lost Caverns of Ixalan Commander | 232 | Rare | $16.99 | — |
2 rulings from Wizards of the Coast
- 23 August 2019If Apex Altisaur fights a creature while either of its abilities is resolving, being dealt damage this way causes its second ability to trigger. It may fight several times in a row this way.
- 23 August 2019If the target creature is an illegal target when Apex Altisaur's last ability tries to resolve, the ability doesn't resolve. If it's a legal target but Apex Altisaur is no longer on the battlefield when the ability resolves (perhaps because it has already died from picking too many fights) the target creature won't deal or be dealt damage.