Draconic Offering

Forecast — {1}{r} or tap an untapped treasure you control and Reveal Draconic Offering from your hand: Create a treasure token. (Activate this ability only during your upkeep and only once each turn.)
Costs {x} less for each treasure sacrificed this turn.
Choose target creature or planeswalker. Draconic Offering deals X damage to all other creatures and planeswalkers.