Official rule text
87.6 The Barony of Letnev’s “Non-Euclidean Shielding” faction Cannon” abilities of their units in the active system. technology allows the Letnev player’s units with the “Sustain Damage” ability to cancel up to two hits instead of one. 89.3 STEP 3—SPACE COMBAT: If two players have ships in the active system, those players must resolve a space combat. RELATED TOPICS: Abilities, Ground Combat, Space Combat
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Source: Twilight Imperium: Fourth Edition - Living Rules Reference: Prophecy of Kings
Expansion: Prophecy of Kings
Version: 2.0
Reference: Rule 87.6