I couldn't miss the chance to practice my drawing!
Attack enemies and drain HP.
Drain Blade (ドレイン剣, Dorein Ken?), also known as Drain Sword, Draining Slash, or simply Drain, is a recurring ability in the series. It is generally part of the Spellblade skillset and allows its user to deal damage and absorb that damage back as HP to the user.
Drain is a level 4 Spellblade ability that costs 6 MP to use. It grants the user the ability to absorb HP from their target, but is inverted against the undead.
Drain Blade is a rank 2 Command Materia that costs 8 AP to use. It can be obtained as a reward for completing Mission 3-3-4, found in Mission 4-2-6, and bought in the Wutai Secret Shop for 10,000 gil. Similar abilities include Power Drain, a rank 5 Command Materia which deals significantly more damage than Drain Blade while costing 16 AP to use, and Aerial Drain, a rank 8 Command Materia that enables Zack to avoid attacks on the ground by jumping into the air and performing the same functions as Drain Blade at the cost of 64 AP. Power Drain and Aerial Drain can be bought in the Wutai Secret Shop for 14,000 gil and 18,000 gil, respectively.
Noctis has been seen using Drain Blade in gameplay demonstrations.
Siphon Sword is an ability for Machina that requires 16 AP and is available after learning Cyclone Drive: Power ↑ II. Machina attacks enemies and drains their HP.
Siphon Sword: Power ↑ requires 6 AP and is available after learning Siphon Sword. It increases the power of Siphon Sword. Siphon Sword: AG ↓ requires 8 AP and is available after learning Siphon Sword: Power ↑. It reduces the AG cost of Siphon Sword.
Drain is a level 4 Sword Magic. It imbues a weapon with an HP absorb effect for ten turns. Attacks with this weapon will absorb HP from the target. It costs 1 MP to use. It can be bought in Starkfort for 1600 pg.
Draining Slash is an ability of the Magic Blade skillset, usable by the Red Mage class. It costs 10 MP to use and inflicts physical damage while absorbing HP.
Drain HP from one enemy
Drain Blade is an single-target ability that costs 7 MP to use and deals hybrid damage (1.4x) and physical damage (0.8x) with HP drain (30%). Dark Knight Cecil learns the skill at Level 56 (5★), whereas Firion acquires it at Level 69 (5★). It is also Ronaldo's Trust Master reward.