Succubus Nurse

[The Nyx Avatar]

LORE:While you control a face-up Fiend-Type monster, you can Special Summon this card from your hand. You cannot activate the effects of other DARK monsters on the field or in your Graveyard while this card is face-up on the field or in the Graveyard; you can pay 1000 Life Points to negate this effect until the End Phase. Once, while this card is in your Graveyard, you can target 1 Fiend-Type monster; it gains 400 ATK. You can discard this card; Special Summon 1 Fiend-Type monster from your Graveyard.

[Trebuchet MS]

From this point on, take a sip for each further Socuteboss joke.

 

While If you control a face-up Fiend-Type monster, you can Special Summon this card (from your hand). You cannot activate the effects of other DARK monsters on the field or in your Graveyard while this card is face-up on the field or in the Graveyard. Once, while this card is in your Graveyard: You can target 1 Fiend-Type monster; it gains 400 ATK. You can discard this card; Special Summon 1 Fiend-Type monster from your Graveyard.

 

The easiest way I can see to bypass this card's debilitating downside is to go straight into an Xyz Summon and do your darndest not to let that card enter the Graveyard. Either that or eventually banish this card for your shenanigans. For such a downside that pseudo-Drains your DARK monsters, you'd expect this card to hold crazy power, but after you use her last effect to revive a Fiend of any size, you're left with a tiny ATK boost and no reliable way to make further use of your DARK monsters. Perhaps add an effect that lets the player lift said pseudo-Drain on their own?

[The Nyx Avatar]

Added effect to lift the DARK negating effect.