Ernest's wild swing shouldn't have impacted anything, but the creature was distracted by its melee with Athan, so surprisingly, Ernest's attack actually manages to inflict 1 damage (the minimum amount for any successful attack.)
Rolls
Leader turns and attacks Rafn - (1d20+3, 1d6+2)
1d20+3 : (14) + 3 = 17
1d6+2 : (1) + 2 = 3
Mob 1 attacks Aengus - (1d20, 1d6)
1d20 : (12) = 12
1d6 : (3) = 3
Mob 2 attacks Agamir - (1d20, 1d6)
1d20 : (8) = 8
1d6 : (2) = 2
Mob 3 attacks Athan - (1d20, 1d6)
1d20 : (15) = 15
1d6 : (1) = 1
Mob 4 attacks Agamir - (1d20, 1d6)
1d20 : (13) = 13
1d6 : (3) = 3
Mob 6 Saving Throw - (1d20+1)
(9) + 1 = 10