Nebula

LRR §59

Rules Reference

A nebula is an anomaly that affects movement and combat.

59.1A ship can only move into a nebula if it is the active system.
- aA ship cannot move through a nebula. That is, a ship cannot move into and out of a nebula during the same movement.
59.2A ship that begins the Movement step of a tactical action in a nebula treats its move value as “1” for the duration of that step.
- aOther abilities and effects can increase this number.
59.3If a space combat occurs in a nebula, the defender applies +1 to each combat roll of their ships during that combat.

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A player cannot retreat (or similar) into a nebula, since it would not be the active system.
The +1 modifier for the defender does not modify anti-fighter barrage, bombardment or space cannon rolls.
The +1 modifier for the defender has no effect during ground combat.
A future rule change will place the ship movement restrictions of anomalies upon all units.
A future rule change will allow ships to move into a nebula when it is not the active system.

Sources