Keyship

The keyship is a massive structure that will rarely spawn in the world

Appearance
Standing 199 blocks tall, the keyship is a pyramid-like structure made of polished andesite, stone brick stairs, a few ladders, and lit by sea lanterns. At the base there are 4 staircases, each ending at a shaft. The player can climb a ladder that leads to the main platform.

Info
Keyships are Forerunner vessels used as warships and later used to re-seed life across the galaxy, following the firing of the Halos. Many of these keyships were lost afterwards. However, prior to the firing of the Halos, one vessel had crashed into the San'Shyuum homeworld, Janjur Qom, carrying a fragment of the rampant A.I. 032 Mendicant Bias. This keyship would later be commandeered by the Reformists when they decided to leave their homeworld.

Spawn Chance
While the stronghold is considered the rarest in-game structure, keyships are even rarer, with no more than one at a time being eligible of spawning. Even then, there is little to no chance that it will spawn at all. If one builds or finds a Forerunner Transport Artifact and goes to the High Charity dimension, he will spawn in the Covenant holy city, just beneath the Forerunner Dreadnought.

Every keyship spawns with 10 San'Shyuum reformists and 10 females. Upon discovery, the San'Shyuum will begin mating and producing children. The only thing you can do then is...prepare for an invasion?