When Volibear attacks and deals 5 damage split however you want, can you use actions before or after the ability resolves to buff/save units, and can you overkill units with the damage?

Ruling: You cannot play action spells during Volibear's ability because it starts a chain where only reaction spells can be played. By the time you can play actions again, the damage has already been dealt, cleanup has been performed, and units have died.

Sequence:

• Volibear's ability starts a chain
• Only reaction spells can be played during the chain
• Targets are chosen when the ability is played
• During resolution, damage is divided among targets
• Each target must be assigned damage greater than 0
• Cleanup is performed and units die
• Only after this can actions be played again

Nuances:

• You can use reaction spells (like Viktor's signature spell) to respond to the ability before it resolves
• If a reaction buffs units, damage is still divided during resolution, but each target must receive at least 1 damage