Q: If a model has an ability that halves damage suffered (rounding up) such as Marneus Calgar’s Armour of Antilochus ability, how is that resolved when I am attacked by several attacks at once? Do I halve the total of all the damage suffered, or do I halve the damage inflicted by each attack separately?

A: Halve the damage suffered by each attack separately. Remember that wounds are allocated one at a time. For example, if Marneus Calgar was wounded by four boltgun attacks (Damage characteristic 1) and each saving throw resulted in a failure, Calgar would suffer 0.5 wounds (which is rounded up to 1) four times, and would therefore lose 4 wounds.