Item from Resident Evil 4 by Capcom
The dominant strain of Las Plagas — whoever hosts it controls every subordinate parasite in the network.
The Master Plaga is the keystone of Saddler's power. Every subordinate Plaga in the region — every Ganado, every mutant, every infected creature — responds to commands transmitted through this organism. It's a biological command-and-control system, and Saddler is the central node. Destroying the Master Plaga doesn't free the hosts (the subordinate parasites continue functioning independently), but it removes coordinated control. Without Saddler's direction, the Ganados become disorganized — still dangerous, but no longer an army. This is why Saddler is the final target, not just a cult leader to arrest.
Larger and more complex than a standard Plaga, the Master Plaga is deeply integrated into its host's biology. In Saddler, it manifests as his ability to transform into a massive spider-like form — the organism is so entwined with his body that they are functionally one entity. When visible, it has a golden-amber coloration and a more developed central body with additional sensory tendrils.
Also known as: Master Plaga, Dominant Plaga, Control Plaga