This lumbering molten rock tortoise breathes out fire and for some odd reason is not immune to fire?
Magma Tortoise (CR 11)
AC 29, touch 7, flat-footed 29 (-1 dex, +22 natural, -2 size)
hp 156 (14d10+84)
Fort +15, Ref +8, Will +5
Immune Earth; Resist Fire 10
Speed 40 ft.
Melee 2 Bites +23 (2d8+10)
Space 15 ft.; Reach 15 ft.
Special Attacks Breath Weapon (1d4+1 rounds, 50-ft. cone, DC 23, 8d6 fire damage)
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
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 When withdrawn he cannot move or attack as long as he remains in this state, a magma tortoise gains a +8 bonus to his Armor Class and a +4 bonus on Reflex saves.