Nebula Duality (Blue)

Deal 1 arcane damage to any target.

Instant -

, discard this: Deal 1 arcane damage to target hero. Create a Lightning Flow token.

Nebula Duality’s second ability can only be activated from your hand. To activate this, show Nebula Duality to all players, then pay the cost of and discard it.
When activating Nebula Duality, you must target a hero as it is a targeted effect. When this activated ability resolves, you will deal 1 arcane damage to that targeted hero. Then you will create a Lightning Flow token, this is not conditional on the damage.
When resolving Nebula Duality’s activated ability, there is no priority between any of the effects generated (e.g. dealing arcane damage, creating a Lightning Flow token).
Discarding this card to pay the cost of activating its first ability counts as activating an instant ability, not as playing an instant.
If the targeted hero no longer exists when Nebula Duality’s activated ability resolves on the stack, you will still create a Lightning Flow token
Effects that prevent damage from a chosen source (e.g. oasis respite) cannot prevent damage from the activated ability since the damage source is a card in the graveyard which is not a legal choice.
Replacement effects that increase the damage of action card effects will increase the arcane damage dealt by Nebula Duality’s instant activated ability (e.g. Aether Wildfire)