The grenades cause daemons and psykers to have I1 for the rest of the phase (when the unit launches an assault), empyrean brain mines causes one model in base contact to make an initiative test, fail means can't attack (after assault moves and before strikes are resolved).
Do you take the test at base initiative or at I1?
The 6th ed. rulebook only tells you to look at the model's profile, nothing specifying about test after or before modifiers.
Subject: Psykout Grenades + Empyrean Brain Mines?