Est

Est is a boss from the Collaboration Scenario. She comes from the game Succubus Quest, and is the final boss of the collaboration.

She's a Nightmare.

Biography
Est first appears when the White Rabbit comes back to the Paradox World after accidentally opening a portal to the wrong world. She reveals that she followed the White Rabbit in hope of finding another world, just like the legends told her.

The White Rabbit attempts to rebuke her, and Est bring her in her own world, the "Land of the Night". The White Rabbit attempts to attack her, but is unsuccessful, and Est tells her that Nightmares can't be attacked like that. She then countera-attack with a pleasure spell that cripples the White Rabbit to the latter's surprise. Having notice the White Rabbit's unusual powers over space-time, she decides to use them for her own pleasure and summon allies from other worlds with the intent to bring her "Land of Night" to the Paradox World.

She only reappears in chapter 12, as the hero goes into the "Land of Night" thanks to a portal created by Daji. The heroes are shocked at the spectacle, as people are having sex with succubi and nightmares in an endless void. She finally reveals herself when the heroes reach the portal used by Est to summon monsters from other worlds, and challenge the heroes to beat her to reach the portal.

However, as a Nightmare, she feeds on the pleasure used to attack her, and she knocks out everyone save for the seven heroes bearing the Proof of Collaboration. The party then beats her once and for all and close the portal. Est is happy she got to enjoy such fine pleasures, and asks the heroes if they did enjoy it too. In any case, she bids farewell and leave the party, saying that she hopes she will get to taste more of those pleasure soon.

She later fled to Grand Noah Colloseum after she lost to the heroes. Later Daji mentions her and how they schemed on using the power of the White Rabbit and they discovered that controlling her will also allowed Daji to explore the realm of the White Rabbit which seems vague on explaining on what kind of enitity she is after being hijacked by her.

Monsterpedia entry
"A being who arrived from another world. Further Details are unknown."

Attacks

 * Ubiquitous Love - One Foe, Certain Hit, Pleasure Attribute, Trance 50%, Seduction 50%, Climax 50%
 * Nightmare - All Foes, Auto Hit, Pleasure Attribute, Trance 50%
 * Succubus Ceremony - One Foe, Pleasure Attribute, Climax 25%
 * Push Down - One Foe (Luka), Bind (2 Turn Break)
 * Succubus Vagina - Rape, One Foe, Pleasure Attribute
 * Energy Drain - Rape, One Foe, Pleasure Attribute, Drain HP
 * Energy Drain - Rape, One Foe, Pleasure Attribute, Drain HP
 * Temptation - All Foes, Magical, Pleasure Attribute, Trance 100%, Seduction 100%, Stun (3) 75%
 * Ethergun - All Foes, Auto Hit, Dispel Buffs
 * Etherfuni - All Allies, Remove debuff

First Fight
For her first form, Est is just another slightly souped up version of Fulbeua. Like all Nightmares, the strategy relies on using pleasure skills to deal damages, buffs to minimize damages, and steadfast healing.

The only status effect that can reliably land is horny, which is definitively a double-edged sword: You will end the fight twice faster, and she will be more likely to take down one of your party members in a single turn.

Second Fight
The main difficulty doesn't come from the fight itself, but from how you prepared to it.

The difficulty of this fight can be directly corroborated to the number of hero-specific items you got on your way in and how much you used the heroes themselves to farm on your way in. Exploring the Château des Romances to get as many character-specific items as possible before facing her is recommended.

The battle itself is relatively classic, as, thankfully, her Nightmare nature is overran by a buff your team is given, allowing you to attack her normally. However, said buff is lost by a character if he dies, even if he's revived afterward. Be very careful. Be sure to have at least ONE hero with a party-wide heal on the frontline like Lauratt. Her fight will be long and tough enough to require a hero on healing duty for the whole duration of the fight.