Does Rabadon cause spells without a damage component (like Stupify, Smoke Screen) to deal damage when targeting an enemy unit?

Ruling: No, bonus damage does not add a damage component to spells that don't already deal damage. Bonus damage increases each instance of damage something deals by X, so it only affects spells that already have damage.

Nuances:

• Rabadon uses "bonus damage" (not "additional damage"), which is the correct templating
• If bonus damage added a damage component to all spells, cards like Discipline would kill your own units, which is not intended
• Ravenborn Tome uses the same "bonus damage" templating and works the same way