Skarrgan Hellkite — ruling 1

You 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.

Skarrgan Hellkite — ruling 2

If Skarrgan Hellkite's ability has two targets and one becomes illegal, the remaining target is dealt 1 damage, not 2.

Skarrgan Hellkite — ruling 3

Once 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.

Skarrgan Hellkite — ruling 4

Riot 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.

Skarrgan Hellkite — ruling 5

If a creature entering the battlefield has riot but can't have a +1/+1 counter put onto it, it gains haste.

Skarrgan Hellkite — ruling 6

If 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.

Skarrgan Hellkite : règles, fonctionnement et interactions (MTG)

Skarrgan Hellkite is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Riot (This creature enters with your choice of a +1/+1 counter or haste.) Flying : 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.

How it works : Skarrgan Hellkite

Original English text — Wizards of the Coast / Scryfall

#1January 25, 2019· Wizards of the Coast
You 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.
No other card is named in this ruling.
#2January 25, 2019· Wizards of the Coast
If Skarrgan Hellkite's ability has two targets and one becomes illegal, the remaining target is dealt 1 damage, not 2.
No other card is named in this ruling.
#3January 25, 2019· Wizards of the Coast
Once 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.
No other card is named in this ruling.
#4January 25, 2019· Wizards of the Coast
Riot 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.
No other card is named in this ruling.
#5January 25, 2019· Wizards of the Coast
If a creature entering the battlefield has riot but can't have a +1/+1 counter put onto it, it gains haste.
No other card is named in this ruling.
#6January 25, 2019· Wizards of the Coast
If 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.
No other card is named in this ruling.