Shambler assault

Shambler Assault is a major threat from the Anomaly DLC, able to occur at monolith level 0. Large groups of humanoid shamblers will come from multiple directions and attack your colony.

Summary

A horde of shambling rotting corpses is approaching. They are intent on attacking your colony. As they exhaust their strange energy, they will begin to collapse within hours. They are attacking immediately.

The shamblers will arrive from multiple directions and will attack immediately, targeting humans. They will "dumb breach" their way towards targets, attacking walls in their way, but not concentrating their attacks on a specific tile. Human and gorehulk shambers will generate.

This event appear can only appear from day 20 onwards, and requires a minimum of 250 raid points. It has a 10 day cooldown.

Analysis

Shambler assaults are relatively safe for pawns, as shamblers are slow, unarmed, melee only, don't target downed pawns, and will dissipate in a few hours. Kiting them is easy. However, assaults can be destructive for the colony. Since shamblers come in huge numbers, in multiple directions, are fairly durable, and will break walls sporadically, they can wreck rooms that are only protected by a single layer of walls. In addition, their rotting corpses will inflict a mood debuff, unless a trait, inhumanized, or an ideoligion counteracts it.

Surrounding your base with a multi-layer perimeter wall will delay the shamblers. After a shambler breaks a wall, it won't necessarily target the next layer of wall right in front of it, so even a two-layer wall will be effective at stalling. Once the shamblers start attacking the perimeter wall, they will be distracted and split up, making it easy to pick off and kite them using ranged weapons.

Distracting the shamblers with non-colonist pawns is another great way to stall for time, while reducing the number of angles the colony needs to defend. Some good ways to get the shambler's attention include the psychic animal pulser (or the other two animal pulsers), calling for miliary aid with a comms console or the empire's permits, or a low quality draw animals ritual. Creating your own shamblers with deadlife dust is effective due to their high durability.

Mountain bases have an easier time with shambler assaults, as they do not attack natural stone, making it easy to funnel them all into a chokepoint. From there, it's possible to fight them. Alternatively, just repairing the colony-made walls and doors may be enough to survive until the shamblers drop.

An exploitative way to deal with a shambler assault is to load all targetable pawns inside transport pods or passenger shuttles; the pawns don't even need to leave the tile. This will result in shamblers having no valid targets and will stop attacking entirely.