Necrose Network

Below the 10th district of Ravnica lies a nest of the Golgari Swarm known as the Necrose Network. Once a twisting mass of giant insect tunnels, now a settlement for those that have embraced decay and rebirth. The nest itself has portions of an older city embedded within including an amphitheater of white marble and a temple to a forgotten goddess. But it's most distinctive feature is the fungal orchard sending its phosphorescent glow (and illuminated spores) in the surrounding area.
The Necrose Network is known for its powerful guild members. The leader of the Writhing Hive (which the Necrose Network is part of) makes her home within this nest. Nesiss Slate Eyes holds court from the ruined temple beyond the fungal orchard. Not far away is the amphitheatr where Orval Shardspear trains his students in the ways of the blade. Within the actual network of tunnels, the nest mother Elga Nightsilk meditates on the will of nature from the queen insect chamber, covered in spider silk. Also a powerful necromancer named Cazna Deathgrasp has a series of chambers where she practices her arts and trains her apprentice.
Within the Swarm the Necrose Network is well known, but few above ground have seen it. This is mostly because the paths to the network are well guarded by Golgari warriors trained by Orval, giant insects and undead. The Denizens of the Necrose Network life in seclusion, waiting for the time when they can bring the proper order of nature to Ravnica. But the most dangerous enemies may not come from outside the guild...

Terminology for Golgari Swarm locations:

• Nest - a small community of swarm agents
• Hive - a collection of 5 to 8 nests, usually under a high shaman
• Colony - a group of hives within the Swarm
• Horde - a group of attackers usually more than 10
• Plague - an army of swarm agents