Makradon turned towards the left. "Feel the fury of the Emperor and his Astartes," his helmet speakers boomed. The echos of his voice were drowned put by the roar as he filled the corridor with burning promethium.
Spoilerdamage:
(1d10)[2] 14p6
(1d10)[9] 21p6
(1d10)[5] 17p6
(1d10)[4] 16p6
(1d10)[6] 18p6
I'm pretty sure I can get them all in the burst, and they need AB > 5 to dodge (if I've got the geometry right.)
Also chance of catching fire etc.