Cockatrice — ruling 1

The ability destroys the creature at the end of the combat, which is after all first strike and normal damage dealing is done. This means that a creature may have to regenerate twice to survive the combat, once from damage and once again at end of combat.

Cockatrice : règles, fonctionnement et interactions (MTG)

Cockatrice 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

Flying Whenever this creature blocks or becomes blocked by a non-Wall creature, destroy that creature at end of combat.

How it works : Cockatrice

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
The ability destroys the creature at the end of the combat, which is after all first strike and normal damage dealing is done. This means that a creature may have to regenerate twice to survive the combat, once from damage and once again at end of combat.
No other card is named in this ruling.