For the more refined vampire, breaking a victim's will is far more satisfying than simply taking their blood.

Bloodtithe Collector

Flying
When this creature enters, if an opponent lost life this turn, each opponent discards a card.

Foundations

Foundations Jumpstart

Innistrad: Double Feature

Innistrad: Midnight Hunt

Bloodtithe Collector's triggered ability cares whether an opponent lost life this turn, not how their life total changed. For example, an opponent who gained 2 life and lost 1 life in the same turn still lost life.