Dragon, Nickel Wyrm (CR 20)

Gargantuan Dragon (Water)
Alignment: Always LE
Initiative: +0; Senses: blindsense 60 ft., darkvision120 ft., low-light vision, and keen senses
Languages: Draconic

AC: 39 (-4 size, +33 natural), touch 6, flat-footed 39
Hit Dice: 34d12+238 (459 hp); DR: 20/magic
Fort +26, Ref +19, Will +23
Speed: 60 ft., fly 200 ft. (clumsy), swim 60 ft.
Space: 40 ft./15 ft.
Base Attack +34; Grapple +59
Attack: 1 bite +43, 2 claws +38, 2 wings +38, 1 tail slap +38, 1 crush +38
Damage: 1 bite 2d8+13, 2 claws 2d6+6, 2 wings 1d8, 1 tail slap 2d6, 1 crush 2d8
Special Attacks/Actions: Breath weapon 19d4 (34)
Abilities: Str 37, Dex 10, Con 25, Int 17, Wis 19, Cha 17
Special Qualities: Immunity to acid, water breathing, Resist energy, Mass irritation, Entangle, Gaseous form, CL 15th, Frightful Presence DC 30, SR 26
Feats: #Feats: 12
Class Skills: Bluff, Hide, Skill points: 108, and and Swim
Advancement: 35-36 HD
Climate/Terrain: Temperate and tropical marsh and swampland
Organization: Solitary (1 dragon, any age), clutch (1d4+1 wyrmlings, very young, young, juvenile, or young adults), family (pair of mature adults and 1d4+1 offspring)
Treasure: Triple Standard

Source: Dragon #356

Breath Weapon (Su): A nickel dragon has one type of breath weapon; a cone of corrosive (acid) gas.

Mass Irritation (Su): An old or older nickel dragon can use this ability twice per day to irritate the skin of living opponents by creating a field of corrosion. Some creatures, such as elementals, have no skin and are immune to this effect. Others, such as oozes and plants, are not affected by irritation to their skin. This is the equivalent of a 3rd-level spell. The targeted creatures must be within 30 feet per age category and must succeed on a Fortitude save or suffer the listed effects. The nickel dragon can choose from one of the following effects.
Itching: The nickel dragon can affect a number of creatures equal to its age category with an intense itching sensation. This itching imposes a -4 penalty on Armor Class and a -2 penalty on attack rolls and Dexterity-based checks for 1d4 rounds. Additionally, an affected creature must succeed on a Concentration check (DC 20 + spell level) to cast a spell. An affected creature can spend a full-round action to scratch itself, thereby ending the effect.
Rash: The nickel dragon can cause a number of creatures equal to half its age category to break out in red welts that cause severe itching. These welts impose a -1 penalty on Charisma-based checks and a -1 penalty on Dexterity-based checks. Each day, the rash spreads, imposing an additional -1 penalty on Charisma-based checks (to a maximum penalty of -10). The effect is permanent but can be dispelled or removed with a remove disease spell or similar effect.

Metalsense (Ex): all ferrous dragons can sense the location and amount of any non-precious metal (precious metals include adamantine, copper, gold, mithral, platinum, and silver) within a distance of 30 feet x the dragon's age category. This makes it nearly impossible to sneak on a ferrous dragon when wearing armor or wielding weapons made of iron or other nonprecious metals. Like blindsense, opponents the dragon can't actually see still have total concealment against the dragon.

Spell-Like Abilities: 3/day - entangle, gaseous form, resist energy.

Water Breathing (Ex): A nickel dragon can breathe underwater indefinitely and can freely use its breath weapon, spells, and other abilities while submerged.

Skills: Bluff, Hide, and Swim are considered class skills for nickel dragons.

Water Subtype

This subtype usually is used for elementals and outsiders with a connection to the Elemental Plane of Water. Creatures with the water subtype always have swim speeds and can move in water without making Swim checks. A water creature can breathe underwater and usually can breathe air as well.