Codex entry: Stealthy Shrieks

Shrieks can move unseen among the enemy. Use the shriek's talent to sneak around a ballista and attack the defenders. When the shriek is stealthed, press H or click on the Hold Position button below your thralls' portraits to order the rest of the party to wait in a safe area. Remember to switch them back to following you once the ballista are no longer a threat.