Soul-Scar Mage — ruling 1

If an effect causes a creature you control to fight a creature an opponent controls, the damage is dealt simultaneously. For instance, if your 2/2 creature fights an opponent’s 4/4 creature, your creature will be dealt 4 damage and your opponent’s creature will have two -1/-1 counters put on it.

Soul-Scar Mage — ruling 2

If a spell or ability an opponent controls causes a source you control to deal noncombat damage to a creature an opponent controls, that damage will be replaced with -1/-1 counters.

Soul-Scar Mage — ruling 3

Soul-Scar Mage’s effect isn’t a prevention effect. Damage that can’t be prevented will be replaced with -1/-1 counters.

Soul-Scar Mage — ruling 4

If multiple prevention and/or replacement effects are trying to apply to the same damage, the controller of the creature that would be dealt damage chooses the order in which to apply them. As examples, an opponent could choose to apply the effect of Djeru’s Resolve and prevent the damage rather than put -1/-1 counters on it; or an opponent could choose to convert the damage to -1/-1 counters before Insult could double it, and then Insult’s effect won’t apply anymore.

Soul-Scar Mage : règles, fonctionnement et interactions (MTG)

Soul-Scar Mage 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

Prowess If a source you control would deal noncombat damage to a creature an opponent controls, put that many -1/-1 counters on that creature instead.

How it works : Soul-Scar Mage

Original English text — Wizards of the Coast / Scryfall

#1April 18, 2017· Wizards of the Coast
If an effect causes a creature you control to fight a creature an opponent controls, the damage is dealt simultaneously. For instance, if your 2/2 creature fights an opponent’s 4/4 creature, your creature will be dealt 4 damage and your opponent’s creature will have two -1/-1 counters put on it.
No other card is named in this ruling.
#2April 18, 2017· Wizards of the Coast
If a spell or ability an opponent controls causes a source you control to deal noncombat damage to a creature an opponent controls, that damage will be replaced with -1/-1 counters.
No other card is named in this ruling.
#3April 18, 2017· Wizards of the Coast
Soul-Scar Mage’s effect isn’t a prevention effect. Damage that can’t be prevented will be replaced with -1/-1 counters.
No other card is named in this ruling.
#4April 18, 2017· Wizards of the Coast
If multiple prevention and/or replacement effects are trying to apply to the same damage, the controller of the creature that would be dealt damage chooses the order in which to apply them. As examples, an opponent could choose to apply the effect of Djeru’s Resolve and prevent the damage rather than put -1/-1 counters on it; or an opponent could choose to convert the damage to -1/-1 counters before Insult could double it, and then Insult’s effect won’t apply anymore.
No other card is named in this ruling.