Support group battle preparation powers

docs/OPTIONAL_ALLIANCE_VICTORY.md

@@ -71,6 +71,18 @@ an implementation interpretation, not an official ruling. The prototype is
 restricted to Basic classic factions without optional modules; other group
 faction benefits and combinations remain unfinished and no lobby exposes it.
 
+## Group Voice and Prescience — 28 October 2026
+
+In the unexposed Basic classic group prototype, Bene Gesserit may Voice an
+opponent of either allied combatant, and Atreides may request Prescience for
+either ally's battle. The existing native preparation order, cancellation,
+answer and control windows remain in place. The same side selection drives
+Truthtrance's native-power opportunity; it never substitutes the other ally
+or allows an ambiguous battle between group members. Extending the printed
+single-ally wording to both group members is provisional. Advanced, expansion
+factions and optional modules remain outside this prototype, and normal
+group starts are not yet available.
+
 ## Group Nexus negotiation — 28 October 2026
 
 **Integrated groundwork, not a selectable game mode.** In a staged Basic