Meskaile is a Death World located within the Jericho Reach. It forms the third in a trio of planets to the trailing edge of the Achilus Crusade's Canis Salient that have come under attack by vanguard elements of Hive Fleet Dagon.
As with Themiskon Point and Scansion Beta, the Achilus Crusade's high command cannot ascertain the reason for the Tyranids' interest in the world, but have been forced to upgrade its strategic rating in response.
Unlike the other two worlds of the triangle, Meskaile is not a Dead World. It is instead the polar opposite, a planet teeming with life, and all of it carnivorous, bloodthirsty and entirely inimical to intrusion by any form of outsider.
The Tyranids' presence on Meskaile was first reported by the Deathwatch near the end of the 41st Millennium. They were discovered in the world in response to a scrap of information rendered on ancient parchment from the depths of Watch Fortress Erioch's Omega Vault.
Whether it was the Tyranids or some other threat that the vault intended the Deathwatch to combat was never discovered, for the Kill-team was forced to extract in the face of overwhelming opposition from both the native denizens of Meskaile and the newly-arrived Tyranids.
Meskaile is now the site of a huge war, one being fought between the invading Tyranids and the carnivorous flora and fauna of the Death World itself. When this fact was first reported to the crusade's high command, it was hoped that the Tyranids would expend their energies fighting a pointless war to capture the world, but that does not appear to be what is happening.
Instead, the Tyranids are undergoing a process of frenzied and sustained hyper-evolution as they battle the denizens of Meskaile, each successive generation getting ever more lethal and developing a prodigious immunity to the numerous poisons utilised by the world's native species.
The servants of the Ordo Xenos are now concerned as to what form of Tyranid may emerge when their conquest of Meskaile is complete, and several voices have called for an Exterminatus to be enacted upon Meskaile before such monstrosities can escape the crucible of their creation.
- Deathwatch: The Achilus Assault (RPG), pg. 108