Blast
(Rule)Description: When you fire a blast weapon roll to hit as normal; if the shot misses it has no effect. If a hit is scored place the blast marker over the target unit so that one model is under the hole to see how many models are affected.
Models whose bases are partially covered by the marker are hit on a D6 roll of 4 ore more, models whose bases are completely covered are hit automatically. The defending player may remove any casualties inflicted from the unit as a whole, not just from models beneath the blast marker.
If a unit is firing multiple blasts, just place one marker after another, resolving the casualties from each blast before placing the next. Remember, casualties can come from anywhere in the unit, not just under the marker.