Cait Sith leaps onto Cloud's shoulder and delivers a calculated strike. Temporarily grants unlimited MP.
Description
Curiosity's End is a synergy ability in Final Fantasy VII Rebirth, used by Cloud Strife with Cait Sith as a synergy partner. It costs three synergy charges each, performs physical damage to a target, and grants them temporarily unlimited MP for a duration.
In the ability's animation, Cait Sith leaps onto Cloud's shoulder as he charges forward to attack. Next, Cait Sith leaps to the air as his moogle follows up to slam him down in an explosive attack.
Obtained[]
Curiosity's End is unlocked on Cloud's folio, and costs 20 SP. It is available at party level 8.
Use[]
Curiosity's End costs three synergy charges each on first use, and four on subsequent uses, and will grant Cloud and Cait Sith unlimited MP for a duration. This allows them to freely use spells, limited only by ATB charges and not by their MP, and by the spells they have in their equipped 
Magic Materia. Cloud has a strong 
Magic Attack pool and good MP, while Cait Sith's magic attack is strong but his MP is a bit more limiting.
Cloud can also use Synchro Cyclone with Tifa Lockhart to achieve the same effect. Cait Sith can achieve it with Kitty Cannonade with Aerith Gainsborough, Mognificent Shot with Red XIII, or Moogle Pinwheel with Yuffie Kisaragi.
The usefulness of this synergy ability will depend on the materia equipped. For example, if Cloud has Healing Materia and 
Magnify Materia (a viable setup given Cloud is often the leader of most parties), he can freely cast 
Curaga on all while MP is unlimited. Cait Sith's magic attack is strong, meaning he can cast offensive spells. Cait Sith and Cloud also both benefit from pairing an elemental magic materia with Elemental Materia for their attacks, and Curiosity's End can unlock their ability to use spells from them freely.
Cait Sith and Cloud both have great potential to be offensive spellcasters, but more often than not will cast supporting or defensive spells. Which way they are built will depend on the chosen weapon equipped.
In Hard Mode, gaining unlimited MP can be more crucial as means to restore MP are more limited. MP Absorption Materia effect will still restore MP to the caster when the spells themselves did not cost anything to cast, letting the player gain MP during the free period. The player may also have the rare and expensive Reraise spell available, perfect to be cast during any MP-free period.
Etymology[]
The name likely alludes to the proverb "curiosity killed the cat".