Cheapest priced copy (Ravnica Allegiance): $0.99 at Card Kingdom, near mint, their price list as of .
Skarrgan Hellkite 
Creature — Dragon · 4/4 · Mythic · Tarkir: Dragonstorm Commander · #233
Riot (This creature enters with your choice of a +1/+1 counter or haste.)
Flying
{3}{R}: This creature deals 2 damage divided as you choose among one or two targets. Activate only if this creature has a +1/+1 counter on it.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.99 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica Allegiance Promos | 114p | Mythic | $3.49 | $7.99 |
| Ravnica Allegiance | 114 | Mythic | $0.99 | $1.99 |
| Tarkir: Dragonstorm Commander | 233 | Mythic | $0.99 | — |
6 rulings from Wizards of the Coast
- 25 January 2019If you choose for the creature to gain haste, it gains haste indefinitely. It won't lose it as the turn ends or as another player gains control of it.
- 25 January 2019You divide the damage as you activate Skarrgan Hellkite's ability, not as it resolves. Each target must be assigned at least 1 damage. In other words, as you activate the ability, you choose whether to have Skarrgan Hellkite deal 2 damage to a single target, or deal 1 damage to each of two targets.
- 25 January 2019If a creature entering the battlefield has riot but can't have a +1/+1 counter put onto it, it gains haste.
- 25 January 2019Riot is a replacement effect. Players can't respond to your choice of +1/+1 counter or haste, and they can't take actions while the creature is on the battlefield without one or the other.
- 25 January 2019Once Skarrgan Hellkite's ability has been activated, it resolves even if all +1/+1 counters are removed from it or if Skarrgan Hellkite leaves the battlefield.
- 25 January 2019If Skarrgan Hellkite's ability has two targets and one becomes illegal, the remaining target is dealt 1 damage, not 2.