Drain is an indirect magic spell in Final Fantasy VIII. The spell steals HP from the enemy and heals the spellcaster, though the latter will also take damage if the target is under the Zombie status or is undead. Drain can also be junctioned to boost stats, and notably, can be junctioned to ST-Atk-J to cause all physical attacks to heal the user slightly.
Drain is a rare spell only drawn from a few enemies. It can be refined from Vampire Fangs using the Guardian Force Leviathan's ability Supt Mag-RF. This makes fighting Red Bats (and their cards) and Glacial Eyes a good way to obtain Drains, as they are a good source of Vampire Fangs.
Drain steals HP from the target and returns it to the caster, with the target's Drain resistance determining how much HP is restored. It is cast using the Magic command, Selphie's Slot Limit Break, or Rinoa's Angel Wing. While both sides will take damage if one is undead or afflicted with Zombie, it will function normally if both meet the criteria. Casting Drain in battle doesn't affect compatibility with Guardian Forces, being one of the few spells to not do so.
When junctioned, Drain provides a meager boost to stats, but more importantly, can be junctioned to ST-Atk-J or ST-Def-J to apply the Drain status effect to all physical attacks or mitigate the amount of HP restored from opposing attacks. The 50% damage increase from Berserk will not affect how much HP is drained.