Deity of Scars — ruling 1

You can pay {B/G} and remove a -1/-1 counter to activate the ability any time you want. Deity of Scars doesn't need to be in danger of being destroyed.

Deity of Scars — ruling 2

Removing a -1/-1 counter from Deity of Scars is a cost of activating its activated ability. You can't activate the ability if there are no -1/-1 counters on Deity of Scars.

Deity of Scars — ruling 3

Deity of Scars's ability causes it to have more toughness when you activate the ability (as a result of losing a -1/-1 counter) and then puts a regeneration shield on it when the ability resolves. If you activate the ability in advance of Deity of Scars being dealt 5 damage, for example, Deity of Scars will be 6/6 before the damage is dealt to it. It won't use the regeneration shield unless it's dealt more damage that turn.

Deity of Scars : règles, fonctionnement et interactions (MTG)

Deity of Scars 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

Trample This creature enters with two -1/-1 counters on it. , Remove a -1/-1 counter from this creature: Regenerate this creature.

How it works : Deity of Scars

Original English text — Wizards of the Coast / Scryfall

#1August 1, 2008· Wizards of the Coast
You can pay and remove a -1/-1 counter to activate the ability any time you want. Deity of Scars doesn't need to be in danger of being destroyed.
No other card is named in this ruling.
#2August 1, 2008· Wizards of the Coast
Removing a -1/-1 counter from Deity of Scars is a cost of activating its activated ability. You can't activate the ability if there are no -1/-1 counters on Deity of Scars.
No other card is named in this ruling.
#3August 1, 2008· Wizards of the Coast
Deity of Scars's ability causes it to have more toughness when you activate the ability (as a result of losing a -1/-1 counter) and then puts a regeneration shield on it when the ability resolves. If you activate the ability in advance of Deity of Scars being dealt 5 damage, for example, Deity of Scars will be 6/6 before the damage is dealt to it. It won't use the regeneration shield unless it's dealt more damage that turn.
No other card is named in this ruling.