FYI : while there are some creatures with special defenses that allow them to ignore specific damage it is typically elemental or magical in nature. Ex : fire heals a flame elemental, skeletons can be killed but have a chance to rise back up...
Des quickly unleashes his prepared arrow only for it to sink into the muddy mass as he knocks his next arrow. The mud does not even react to the attack and continues on its charge, slamming into John who stops it with his shield. Cass calls to upon the spirits to answer he summons but the flames are slow to respond to her and do not manifest a corporeal spirit.
Rolls
Mud beast attack vs John - (3d6, 3d6)
3d6 : (212) = 5
3d6 : (421) = 7