Red XIII and Yuffie sync up and attack in tandem. Raises their limit levels.
Description
Hack and Slash is a synergy ability in Final Fantasy VII Rebirth, used by Red XIII with Yuffie Kisaragi as a synergy partner. It costs three synergy charges each, deals magic damage to a foe with a wide area-of-effect around them, and boosts their limit level by 1, giving them new possible limit breaks. This can be raised up to a limit level of 3 once this is unlocked from their folio.
In the ability's animation, Yuffie and Red XIII perform a flurry of attacks, launching the foe into the air, before bringing them crashing down.
Obtained[]
Hack and Slash is unlocked on Red XIII's folio, and costs 15 SP. It is available at party level 5.
Use[]
Hack and Slash costs three synergy charges each on first use, and four on subsequent uses, and will boost Red XIII and Yuffie's limit level by 1 until they are KO'd in battle. At limit level 2, Red XIII's limit break is Howling Moon, while Yuffie's is Bloodbath. At level 3, Red XIII's limit break is Wrath of the Land, while Yuffie's is Devastation, though the player will have to unlock these in the folio at a high party level. Red XIII benefits greatly from being able to access his higher-level limit breaks, while Yuffie does somewhat.
Both Red XIII and Yuffie also have other partner combinations to boost their limit level. Red XIII can use Overfang with Cloud Strife, Bestial Barrage with Tifa Lockhart, or Planetary Roar with Aerith Gainsborough. Yuffie can use Maelstrom Strike with Cloud, or Ninja Carbine with Barret.
Red XIII's higher-level limit breaks do deal more damage, but also have different strategic uses. His level 1 limit break, Bloodfang, deals damage while healing him, while Howling Moon grants him a longer Vengeance Mode, during which he can use Siphon Fang and also heal himself while attacking. His level 3 Wrath of the Land limit break simply deals damage to all enemies.
For Yuffie, increasing her limit level simply gives her stronger attacks. Yuffie is a damage dealer who thrives on performing combos of multiple attacks quickly, and her balanced attributes allow her to be built either toward physical damage, magic damage, or a mix of both. If built toward physical damage, her limit breaks can be a decent source of damage for her, but if built toward magic damage, it is less of a priority to boost her limit level.
If 
Expeditionary Medal is equipped on either party member, they will start at limit level 2, meaning Hack and Slash can only boost their level up to 3. If Enhanced Expeditionary Medal is equipped, they will start at limit level 3, meaning Hack and Slash will have no effect on them; as such, the ability should only be used to boost the other's limit level, or for the damage output. Other accessories (namely Silver Brawler's Gloves, Golden Brawler's Gloves, Draconic Ring, Enhanced Draconic Ring, Limit Booster, Transference Module, Gi Warrior's Charm, and Gotterdammerung) and 
Limit Support Materia can also raise the rate limit gauges increase in battle, allowing them to use their limit breaks more regularly and get more from boosting the limit level.
Etymology[]
Hack and slash is a video game term that describes combat with melee-based weapons (such as swords).