Seven-Headed Juggernaut (CR 15)

Gargantuan Construct
Alignment: Always neutral
Initiative: +2 (Dex)
Languages: Cannot speak

AC: 34 (-4 size, +2 Dex, +34 natural), touch 8, flat-footed 32
Hit Dice: 45d10+60 (hp 307 hp); DR: 15/magic adamantine
Fort +9, Ref +9, Will +4
Speed: 30 ft.
Space: 20 ft./20 ft.
Base Attack +33; Grapple +56
Attack: Bite +8 melee
Full Attack: Bite +8 melee
Damage: Bite 2d8+22/18-20/x3)
Special Attacks/Actions: Augmented critical, breath weapons, trample 2d6+22 plus 4d6 fire
Abilities: Str 40, Dex 14, Con -, Int -, Wis 11, Cha 1
Special Qualities: Construct traits, heat, immunity to magic
Advancement: 46-60 HD (Gargantuan) 60-135 HD (Colossal)
Climate/Terrain: Any
Organization: Solitary
Treasure/Possessions: None

Source: Dungeon #124

Augmented Criticals (Ex): The seven-headed juggernaut's bite threatens a critical hit on a roll of 18-20 and inflicts X3 damage on a confirmed critical hit.

Breath Weapons (Su): Six of the juggernaut's heads can employ breath weapons - each head may use its breath weapon once per round. The save DCs for all breath weapons are Constitution-based. The breath weapons have the following effects:

Trample (Ex): Reflex half DC 47. The save DC is Strength-based. The additional fire damage is from contact with the creature's superheated underbelly.

Heat (Su): When active, the juggernaut's underbelly glows a cherry red as it gives off tremendous heat. Any creature that attacks the juggernaut with natural weapons, unarmed strikes, or light weapons has a 50% chance of taking 4d6 fire damage from the heat.

Immunity to Magic (Ex): The seven-headed juggernaut 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.

Cold spells that target the juggernaut deal no damage, but they do slow it and suppress its heat for a number of rounds equal to the level of the spell.

The juggernaut is affected normally by rust attacks, such as that of a rust monster or a rusting grasp spell.

When active, the seven-headed juggernaut typically charges into melee, beginning combat with a trample attack. It can actually only bite with one of its heads, but the other six can generate devastating breath weapon attacks, each once per round. The seven-headed juggernaut uses these weapons against ranged foes.