Ragemonger

Minotaur spells you cast cost {B}{R} less to cast. This effect reduces only the amount of colored mana you pay. (For example, if you cast a Minotaur spell with mana cost {2}{R}, it costs {2} to cast.)

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6o5n9831vdpb1hum15ib6q.