Cheapest priced copy (Outlaws of Thunder Junction Commander): $0.99 at Card Kingdom, near mint, their price list as of .
Ukkima, Stalking Shadow 
Legendary Creature — Whale Wolf · 2/2 · Mythic · Outlaws of Thunder Junction Commander · #247
Partner with Cazur, Ruthless Stalker (When this creature enters, target player may put Cazur into their hand from their library, then shuffle.)
Ukkima can't be blocked.
When Ukkima leaves the battlefield, it deals X damage to target player and you gain X life, where X is its power.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.99 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2020 | 17 | Mythic | $1.99 | $0.99 |
| Outlaws of Thunder Junction Commander | 247 | Mythic | $0.99 | — |
3 rulings from Wizards of the Coast
- 17 April 2020If the target player is an illegal target by the time Ukkima's last ability tries to resolve, the ability won't resolve. You won't gain any life.
- 17 April 2020Use Ukkima's power as it last existed on the battlefield to determine how much damage it deals and how much life you gain. If that number is negative, it deals no damage and you gain no life.
- 17 April 2020If your life total is brought to 0 or less at the same time that Ukkima is dealt lethal damage, you lose the game before the last ability goes on the stack.