Trophy Hunter — ruling 1

The second ability checks whether a creature being put into a graveyard (a) currently has flying and (b) was dealt damage earlier this turn by Trophy Hunter. It doesn't matter whether Trophy Hunter dealt the damage that caused the creature to be destroyed, whether the damage from Trophy Hunter was dealt in combat or via its activated ability, or who controlled the creature.

Trophy Hunter : règles, fonctionnement et interactions (MTG)

Trophy Hunter 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 deals 1 damage to target creature with flying. Whenever a creature with flying dealt damage by this creature this turn dies, put a +1/+1 counter on this creature.

How it works : Trophy Hunter

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2005· Wizards of the Coast
The second ability checks whether a creature being put into a graveyard (a) currently has flying and (b) was dealt damage earlier this turn by Trophy Hunter. It doesn't matter whether Trophy Hunter dealt the damage that caused the creature to be destroyed, whether the damage from Trophy Hunter was dealt in combat or via its activated ability, or who controlled the creature.
No other card is named in this ruling.