Syll'Esske is the name given to an unholy union of a Slaanesh Daemon Prince and one of the Dark Prince's Daemon Heralds.
The Daemonic Herald Syll Lewdtongue was once shunned by those in Slaanesh's court for growing too attached to those meant to be tempted into their own destruction. Syll's affection for these mortals would eventually lead to glory when a mortal gladiator-slave in Slaanesh's garden known as Esske caught the Herald's eye. Esske's newfound patronage allowed him to ascend all the way to Daemonhood, only to be dismissed by Slaanesh Daemon courtiers due to his status as a former mortal. In response, Syll and Esske joined forces to take revenge on those that had shunned them, working closely in battle to compliment each others strengths. Fighting to the throne of Slaanesh itself, the two bound their fates in a dark pact. They became a symbiotic entity known as Syll'Esske, fighting with deadly synchronicity. The alliance which had made them outsiders before, now paved the way for their mutual ascension.
- 1: Warhammer Community (last accessed 24 April 2019)