Potion of Despair

• Type: Dark Magic, Potion, Horcrux Defence
• Owners: The basin containing the potion was created and effectively owned by Lord Voldemort.
• Maker: Lord Voldemort

The Potion of Despair is an emerald green liquid that glows with a faint, phosphorescent light. It was discovered by Albus Dumbledore and Harry Potter filling a large, carved stone basin inside the sea cave where Lord Voldemort hid the Horcrux of Salazar Slytherin's Locket. The potion is a key component of the Horcrux's magical protection.

The potion serves as one of the most cruel and powerful magical defences known. Its properties are designed to incapacitate and torment any who would seek to retrieve the object submerged within it.

• Primary Effect: The potion's main function is to induce extreme psychological torment. A wizard or witch who drinks it is forced to relive their worst memories and experiences, leading to immense pain, regret, and despair. Albus Dumbledore described it as a potion that “brings about such terrors, such pain, that the person is unlikely to survive it.”
• Secondary Effect: It causes an unbearable, burning thirst in the drinker. This thirst cannot be quenched by magically conjured water, as any Aguamenti spell cast on the basin or to create drinking water is ineffective. This effect cruelly tempts the drinker or their companion to take water from the surrounding enchanted lake, which awakens the horde of Inferi lying in wait.
• Method of Retrieval: The potion cannot be parted, vanished, transfigured, scooped, or siphoned away. The only way to empty the basin and reach the Horcrux at the bottom is for someone to drink the entire volume of the liquid. The potion magically replenishes itself if removed by any means other than consumption.

The Potion of Despair was created by Lord Voldemort sometime after he created his locket Horcrux. He chose a remote sea cave he had visited as a boy and placed the Horcrux inside a basin filled with this potion. To test his defences, Voldemort conscripted the house-elf Kreacher. He forced Kreacher to drink the potion, and after the house-elf had drained the basin, Voldemort dropped the locket in and allowed the potion to refill. He then abandoned the tormented and dehydrated Kreacher on the central island, assuming he would perish. However, Kreacher was able to escape using house-elf magic, which is not bound by the same anti-Apparition charms that affect wizards. Kreacher reported these events to his master, Regulus Black. Disgusted by Voldemort's cruelty and determined to destroy the Horcrux, Regulus returned to the cave with Kreacher. He drank the potion himself, ordering Kreacher to take the locket and destroy it once the basin was empty. Weakened and maddened with thirst, Regulus Black crawled to the lake's edge and was dragged to his death by the Inferi. Years later, in 1997, Albus Dumbledore and Harry Potter journeyed to the cave to retrieve the Horcrux. Dumbledore, despite his advanced age and power, was forced to drink the potion with Harry's help. He suffered immensely, crying out in agony as he relived his tragic past involving his family, particularly his sister Ariana Dumbledore, and his history with Gellert Grindelwald.

The Potion of Despair is a powerful symbol of Lord Voldemort's cruelty and his deep understanding of debilitating forms of Dark Magic. Its existence highlights his preference for psychological torment over simple lethal curses as a means of defence. The potion plays a critical role in the climax of Harry Potter and the Half-Blood Prince. The ordeal of drinking it severely weakens Albus Dumbledore, leaving him physically and magically vulnerable. This weakness is a direct contributing factor to his subsequent death at the hands of Severus Snape atop the Astronomy Tower. The event also provides Harry with a harrowing insight into the hidden pain and regrets of his seemingly infallible mentor. Furthermore, the story of Regulus Black's sacrifice, centered on his willingness to drink the potion, is a key element in redeeming his character and motivating Kreacher to aid the fight against Voldemort.

• In the film adaptation of Harry Potter and the Half-Blood Prince, Dumbledore's torment while drinking the potion is shown, but the specific nature of his visions is not made clear to the viewer. The potion's appearance and the thirst it induces are depicted in a manner consistent with the novel (film).