§ 715.4 Core Rules PDF (officieel)

If no damage was Dealt, then Bonus Damage will not apply. Example: Teemo, Strategist is a unit that reads in part “When I defend, choose an enemy unit here and reveal the top 5 cards of your Main Deck. Deal 1 to that unit for each card with Hidden revealed this way, then recycle the revealed cards.” He has Rabadon’s Deathcrown attached to him. An enemy unit moves to the battlefield where Teemo is located and a combat opens there. Teemo’s controller reveals the top 5 cards of their Main Deck and reveals no cards with Hidden. Although the ability has 3 Bonus Damage from Rabadon’s Deathcrown, no deal action is performed for the Bonus Damage to apply to.