Roil's Retribution deals 5 damage divided as you choose among any number of target attacking or blocking creatures.
You choose how many targets Roilâ€™s Retribution has and how the damage is divided as you cast the spell. Each target must receive at least 1 damage.
If some, but not all, of the targets become illegal by the time Roilâ€™s Retribution tries to resolve, the original division of damage still applies, but no damage is dealt to illegal targets. If all the targets are illegal, the spell wonâ€™t resolve.