If I recycle 8 runes with Bullet Time, is it 8 damage to each enemy unit or 8 damage split across enemy units at a battlefield?

Ruling: Bullet Time deals 8 damage to each enemy unit at the battlefield, not split across them.

Nuances:

• You don't pay the Power cost for Bullet Time's ability until the spell starts to resolve, so opponents must use reactions before knowing how much Power you'll invest
• Opponents cannot use Defy after seeing how much Power is paid, because Defy targets the card on the chain before the Power payment happens
• You can tap for energy while resolving Bullet Time's ability to pay the Power cost