Dark Nephthys' first effect is an Ignition Effect. Removing DARK monsters from play is a cost.
The first effect of "Dark Nephthys" is an Ignition Effect. Removing DARK monsters from play is a cost.
You can activate the first effect of "Dark Nephthys" while "Banisher of the Light" or "Macro Cosmos" is face-up, but "Dark Nephthys" will be removed from play.
"Dark Nephthys" effect to Special Summon itself starts a Chain.
The owner of "Dark Nephthys" Special Summons it, even if their opponent activated its first effect.
The third effect of "Dark Nephthys" activates whenever it is Special Summoned, including by another card's effect. It is not optional.