Whothe Ordo Xenos and its Chapters (the Inquisitorial masters the Watch serves and the loyal Space Marine Chapters that second it their veterans - an Inquisition war-cell, a Chapter strike force, any Imperial force sworn to the extermination of the alien and bound to the Watch by the requisition it channels)
Termscampaign-level alliance: while it holds, the Watch is the Ordo Xenos armoury made flesh - the ally may requisition special-issue ammunition options from the Deathwatch (cross-referenced, never duplicated), and once per campaign phase lends the Kill Team a single veteran fighter or a war-cell's worth of intelligence (a free prey pre-declaration before deployment). In return the Watch gains bonus Reputation for a battle won by eliminating a declared xenos prey; the alliance runs until the vigil is called off or the pact is broken
The Deathwatch stand with the Ordo Xenos and the Chapters that second them their veterans — an Inquisitorial war-cell, a loyal Chapter strike force, any Imperial force sworn to the extermination of the alien and bound to the Watch by the requisition it channels.
While the alliance holds, the Watch is the Ordo Xenos armoury made flesh: the ally may requisition special-issue ammunition options from the Deathwatch — cross-referenced, never duplicated — and once per campaign phase lends the Kill Team a single veteran or a war-cell's worth of intelligence, a free reading of the enemy before deployment. In return the Watch gains bonus reputation for any battle won by eliminating a declared xenos prey. The pact runs until the vigil is called off or the bond is broken.
The Swarm That Trades Bodiesalliance
Whothe swarm that trades bodies (an attrition horde built on cheap, numberless fighters - a Tyranid brood, a Genestealer cult's uprising, an Ork mob, any force that wins by spending more bodies than the enemy can kill; the natural prey the Watch out-ammunitions and the single matchup a veteran-only Kill Team most dreads)
Termscampaign-level feud: while it stands, the Deathwatch gain bonus Reputation for a decisive win in which they eliminated the swarm's synapse/leader body and broke the horde, but the swarm gains Reputation for every battle in which it forced the Watch to spend a veteran it cannot replace, whatever the mission's result; the feud runs until one side is driven off the contested world
The natural enemy of a veteran-only Kill Team is the horde that wins by spending more bodies than the Watch can kill — a Tyranid brood, a Genestealer cult's uprising, an Ork mob, any force built on cheap and numberless fighters. It is the prey the Watch out-ammunitions, and the single matchup it most dreads.
This is a feud, not a friendship. While it stands, the Deathwatch gain bonus reputation for a decisive win in which they eliminated the horde's synapse or leader and broke it — but the swarm gains reputation for every battle in which it forced the Watch to spend a veteran it cannot replace, whatever the mission's result. The feud runs until one side is driven off the contested world.