Comet proccing from attacks that don't deal damage

[GAMEPLAY] Keystone Arcane Comet procs even if Fiora parries an attack and therefore takes no damage.

Under Arcane Comet it states that "dealing damage to enemy champions..." which would logically mean that if you prevent damage from being taken, no comet should appear. Yet when playing Fiora vs Sion, Sion's E automatically procced comet even if no damage was taken because of Fiora's W. This happened to me during one game several times and the comet was flung so quickly that it's not even possible here that corrupting potion was the cause of this damage proc (even though Fiora's W should prevent that from happening also). Cannot say if this bug is purely for Fiora (or damage-prevention in general) or does Arcane Comet slightly differ from what is mentioned in it's text (maybe comet happens when an enemy champion is hit with an ability instead of taking damage from an ability) or maybe this is why Sion is broken enough to have a positive winrate against every toplane champion.