Devouring Light

The declare blockers step is the last chance to cast Devouring Light before creatures deal their combat damage. However, a creature remains an attacking or blocking creature during the combat damage step and end of combat step. Devouring Light may be cast targeting such a creature during those steps, after the creature has dealt combat damage.

When calculating a spell's total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Convoke applies after the total cost is calculated. Convoke doesn't change a spell's mana cost or mana value.

Tapping a multicolored creature using convoke will pay for {1} or one mana of your choice of any of that creature's colors.