Mage-Ring Responder — ruling 1

The last ability triggers and resolves before blockers are declared. If the target creature is destroyed by the damage, it won’t be on the battlefield to block.

Mage-Ring Responder : règles, fonctionnement et interactions (MTG)

Mage-Ring Responder 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

This creature doesn't untap during your untap step. : Untap this creature. Whenever this creature attacks, it deals 7 damage to target creature defending player controls.

How it works : Mage-Ring Responder

Original English text — Wizards of the Coast / Scryfall

#1June 22, 2015· Wizards of the Coast
The last ability triggers and resolves before blockers are declared. If the target creature is destroyed by the damage, it won’t be on the battlefield to block.
No other card is named in this ruling.