Originally Posted by
Lerra
In a game with infiltrators and units with scout, when does the tyranid player have to decide which terrain piece the Ymgarl genestealers are lying dormant in?
From the Tyranid codex: "Ymgarl Genestealers can elect to start the game in a dormant state. . . . If you choose to do this, the brood is not deployed with the rest of the army. Instead, after both sides have deployed, secretly write down which piece of terrain they are lying dormant in."
Infiltrate USR: "Units with this special rule are deployed last, after all other units (friends and foe) have been deployed.
Scout USR: ". . . after both sides have deployed (including infiltrators), but before the first player begins his first turn, any scouts may make a normal move."
Both the Ymgarl Genies and units with Scout trigger "after both sides have deployed". I haven't been able to find an answer to this question from RAW.