Mushroom Golem--Montporte Dungeon Campaign Critter
Armor Class: 6 
Hit Dice: 50 hit points
Attacks: 2 fists (3d6)
Saving Throw: 3
Special: Immune to most spells; Immune to normal fire; Resistant to magical fire; Hit only by magical weapons
Challenge Level/XP: 14/2600
Mushroom golems are huge animated mushrooms with limbs fabricated from mushroom stems.
COMBAT: Mushroom golems attack as 6 hit dice creatures, getting two attacks per round with their giant fists.
MAGIC IMMUNITY: Mushroom golems are immune to most forms of magic. They are also subject to damage from fire-based spells (see below).
FIRE IMMUNITY/RESISTANCE: Mushroom golems are immune to normal fire and gain a +2 to saving throws versus magical fire.
IMMUNE TO NON-MAGICAL WEAPONS: Mushroom golems are immune to non-magical weapons and can only be hit by +2 or better magical weapons. They are not immune from attacks from “outsiders,” such as dragons, fey, and demons, although they do gain a +3 armor class bonus against such creatures.