This lumbering molten rock tortoise breathes out fire and for some odd reason is not immune to fire?
Magma Tortoise (CR 11)
XP 12,800
N Huge Magical Beast (Fire, Reptilian)
Init -1; Senses Darkvision 60 ft., low-light vision, scent; Perception +21
DEFENSE
AC 29, touch 7, flat-footed 29 (-1 dex, +22 natural, -2 size)
hp 156 [224] (14d10+84)
Fort +15, Ref +8, Will +5
Immune Earth; Resist Fire 10
Weakness Ice
OFFENSE
Speed 40 ft.
Melee 2 Bites +23 (2d8+10)
Space 15 ft.; Reach 15 ft.
Special Abilities Magic Shell, Shell
Special Attacks Breath Weapon (1d4+1 rounds, 50-ft. cone, DC 23, 8d6 fire damage)
STATISTICS
Str 30, Dex 8, Con 22, Int 2, Wis 12, Cha 6
Base Atk +14; CMB +24 (+26 vs. bull rush); CMD 33 (35 vs. bull rush; 37 vs. trip)
Feats Awesome Blow, Awesome Charge, Cleave, Improved Bull Rush, Power Attack, Vital Strike, Weapon Focus (bite)
Skills Acrobatics +18, Climb +28, Perception +21, Survival +19
SPECIAL ABILITIES
Critical Attack (Ex)
Once every 1d2 rounds as a standard action, the magma tortoise can inflict more pain than normal. If they succeed at hitting with their bite attack, the damage is 2d8+10 x 1.5 for total damage.
Magic Shell (Su)
As a move action, a fell tortoise can completely withdraw into its shell, leaving him almost completely impervious to attack. When withdrawn he cannot move or attack as long as he remains in this state, a magma tortoise gains an all Elemental Resist of 14. This cannot be active during Shell.
Shell (Su)
As a move action, a magma tortoise can completely withdraw into its shell, leaving him almost completely impervious to attack. When withdrawn he cannot move or attack as long as he remains in this state, a magma tortoise gains a +8 bonus to his Armor Class and a +4 bonus on Reflex saves.