Omios

Hi everyone, The Cometstrike Sceptre ability of the Celestant Prime deals d3 mortal wounds to units within 6" of a point on the battlefield. Do I roll seperate for each unit or 1 dice for all of them. It's important because you can change the d3 roll to 3 via Orrery of Celestial Fates . And what about abilities like Thunderblast from the Knight-Heraldor etc? Also just 1 dice roll for all Units? Thanks.