Cleon
Legend
How about the line reads...
Fire, Both Mundain and from spells function normally against a cloth golem and do 50% more fire damage.
No need to mention mundane fire, since that's already covered by their vulnerability.
How about:
Special Qualities: Construct traits, damage reduction 5/slashing [?], darkvision 60 ft., immunity to magic, low-light vision, vulnerability to fire
Immunity to Magic (Ex): A cloth golem is immune to any spell or spell-like ability that allows spell resistance. In addition, certain spells and effects function differently against the creature, as noted below.
Fire spells function normally against a cloth golem and their fire damage is increased by 50% because the golem has vulnerability to fire.
A mending spell heals a cloth golem of 1d4 points of damage.
A make whole spell heals a cloth golem of 2d6 points of damage.
A fabricate spell heals a cloth golem of all damage.