Kastrian Firing Line

Convoke. (Your creatures can help cast this
spell. Each creature you tap while casting this spell
pays for {1} or one mana of that spell color.)
Repeat the following process X times.
Put a -1/-1 counter on target creature.
In the aftermath of the battle, the weary citizens of
Unvik spent days searching through the bolt-riddled
bodies lying knee deep on Harbor Street.