In the context of White Wolf Game Studio's vampire books and role-playing games from the World of Darkness, diablerie takes place when a vampire drinks not only all the blood of another vampire but also her/his soul, generally in order to increase his/her own powers. A vampire who engages in diablerie is known as a diablerist.
Old World of DarknessIn Vampire: The Masquerade and related media, the strength of vampirical powers is often correlated with the vampire's generation, i. e. the generational distance between the original vampire Caine and the vampire, where Caine was the first generation, his childer were the second, etc. (in The Masquerade, the default generation for starting characters is the 13th). On each successive generation these powers become more and more diluted as a result of a curse set upon the Third Generation by Caine himself. By committing diablerie, a vampire can absorb those purer powers from a vampire of an earlier generation, effectively decreasing his/her own generation (the victim, of course, experiences the final death in the process).
Diablerie is explicitly forbidden by the vampiric tradition and is considered a crime by the Camarilla, but it is a fairly common practice in the Sabbat. In the past, the Assamite clan devoted its energies to diablerie in order to gain power, until the Tremere placed a magic curse on them, by virtue of which Assamites became physically harmed by the act of drinking vampire blood. Nevertheless, this curse did not stop the Assamites from continuing their practices by indirect means. It was finally broken in 1998 by the Methuselah Ur-Shulgi, childe of the Assamite Antediluvian Haqim, who arose from torpor and took command of the clan. It must also be noted that diablerie was not unknown to the Tremere (the clan's founder committed diablerie on Saulot, the Antediluvian founder of clan Salubri).
Vampires with the Discipline of Auspex are supposed to be able to recognize diablerists by the characteristic dark veins in their aura.
In the game Vampire: The Dark Ages, set in the 13th century, this practice was known as Amaranth. When a blood hunt was to be declared, it was customary to send the victim a flower of amaranth a week in advance. The sire traditionally killed his childe through diablerie.
New World of DarknessIn the new vampire game, Vampire: The Requiem, the concept of generation is no longer used. Instead, the power of an individual vampire corresponds to that vampire's Blood Potency, which increases as they age (and can also decrease if they spend sufficient time in torpor). Engaging in diablerie may increase Blood Potency if the victim has a higher blood potency.
Furthermore, the rulebook states that Amaranth is not just the drinking of another vampire's vitae, but of their very soul. In some cases, memories or personality traits may transfer into the diablerist. Diablerie is specifically forbidden in the Requiem, and the punishment for a known diablerist is Final Death.
Diablerie is the second of three forbidden acts in Vampire: The Requiem, along with siring childer without permission and breaking the Masquerade (like Camarilla in Vampire: The Masquerade). Committing diablerie results in an automatic decrease in Humanity.
diablerie in Catalan: Diablerie
diablerie in Spanish: Glosario de Vampiro: La Mascarada#Diablerie
diablerie in Italian: Diablerie
diablerie in Russian: Диаблери
diablerie in Chinese: 獵魂（新黑暗世界）