Rix Maadi Reveler

Spectacle {2}{B}{R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
When Rix Maadi Reveler enters, discard a card, then draw a card. If Rix Maadi Reveler's spectacle cost was paid, instead discard your hand, then draw three cards.

Ravnica Allegiance

Spectacle {2}{B}{R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
When Rix Maadi Reveler enters the battlefield, discard a card, then draw a card. If Rix Maadi Reveler's spectacle cost was paid, instead discard your hand, then draw three cards.

Ravnica Allegiance Promos

If you have no cards in hand, you won't discard any cards, and then you'll draw one or three cards as appropriate.

Rix Maadi Reveler is only red. It's not black, even if you cast it for its spectacle cost.

A card's spectacle cost is the same no matter how much life your opponents lost or how many opponents lost life.

Damage dealt to a player causes that player to lose that much life.

In a multiplayer game, if an opponent loses life and later that turn leaves the game, you can cast a spell for its spectacle cost. (If a player leaves the game during their turn, that turn continues without an active player.)

Spectacle cares only that an opponent lost life during the turn, not that the opponent's life total is currently lower than it was. For example, if an opponent loses 1 life and then gains 2 life in the same turn, you can cast a spell for its spectacle cost that turn.

Spectacle doesn't change when you can cast the spell. For example, you can't cast a sorcery with spectacle during an opponent's turn unless another effect allows you to do so, even if that player has lost life this turn.

To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as a spectacle cost), add any cost increases, then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.