Goblin Psychopath — ruling 1

The ability triggers when it attacks or block and resolves before combat damage is assigned. This gives you a chance to possibly get rid of it before it hurts you.

Goblin Psychopath : règles, fonctionnement et interactions (MTG)

Goblin Psychopath 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

Whenever this creature attacks or blocks, flip a coin. If you lose the flip, the next time it would deal combat damage this turn, it deals that damage to you instead.

How it works : Goblin Psychopath

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
The ability triggers when it attacks or block and resolves before combat damage is assigned. This gives you a chance to possibly get rid of it before it hurts you.
No other card is named in this ruling.