I've got a group of 14th level characters, and we're going to be doing some different combats to playtest the mythic rules this Sunday. If you're in my Slumbering Tsar game, please don't read the rest of this post.
The players are going to be 14th level with 7 mythic tiers. I want to throw a mythic black dragon at them (I'll get to use my huge black dragon piece finally), so I took a Black Dragon, Wyrm (CR 17) and added 7 mythic ranks to it. This is what I came up with:
Mythic Black Dragon, Wyrm CR 24/MR 7
XP 1228800
CE Huge dragon (water), mythic
Init +23/+3; Senses blindsense 60 ft., darkvision 120 ft., dragon senses, low-light vision; Perception +36
Aura terrifying presence (330 ft., DC 27)
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Defense
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AC 48, touch 7, flat-footed 48 (-1 Dex, -2 size, +41 natural)
hp 394 (24d12+238); fast healing 5
Fort +21, Ref +13, Will +19
DR 20/magic and epic; Immune acid, paralysis, sleep; SR 35
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Offense
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Speed 60 ft., flight (200 feet, poor), swimming (60 feet)
Melee Bite +37 (2d8+21 plus 4d6 acid), 2 claws +36 x2 (2d6+14), tail +34 (2d6+21), 2 wings +34 (1d8+7)
Space 15 ft.; Reach 10 ft. (15 ft. with bite)
Special Attacks breath weapon (100-ft. line, 22d6 acid, every 1d4 rounds, DC 29), corrupt water, crush
Spell-Like Abilities (CL 22nd)
At will - darkness (110 ft. radius), insect plague, plant growth
Sorcerer Spells Known (CL 13):
6 (4/day) true seeing, acid fog
5 (7/day) persistent image (DC 20), wall of force, cloudkill (Mythic)(DC 20)
4 (7/day) black tentacles, hallucinatory terrain, enervation, dimension door
3 (7/day) heroism, haste, dispel magic (Mythic), stinking cloud (DC 18)
2 (7/day) cat's grace, acid arrow, bull's strength, mirror image, invisibility (Mythic)
1 (8/day) shield, mage armor (Mythic), color spray (Mythic) (DC 16), true strike, protection from good
0 (at will) resistance, read magic, mending, mage hand, detect magic, dancing lights, prestidigitation, message, light
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Statistics
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Str 39, Dex 8, Con 25, Int 18, Wis 21, Cha 20
Base Atk +24; CMB +40; CMD 49 (53 vs. Trip)
Feats Alertness, Combat Expertise (Mythic), Combat Expertise, Flyby Attack, Greater Vital Strike, Improved Initiative, Improved Vital Strike, Multiattack, Mythic Spells, Power Attack (Mythic), Power Attack, Skill Focus (Stealth), Snatch, Vital Strike, Vital Strike (Mythic), Weapon Focus (Bite)
Skills Acrobatics -1 (+11 jump), Fly +18, Handle Animal +29, Intimidate +32, Knowledge (arcana) +31, Knowledge (geography) +31, Knowledge (history) +31, Perception +36, Sense Motive +7, Spellcraft +31, Stealth +24, Swim +49
Languages Common, Draconic, Giant, Goblin, Orc
SQ acid pool, acidic bite, mythic power (1d10, 7 points), swamp stride, water breathing
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Special Abilities
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Acid Pool (Su) An ancient or older black dragon can use its breath weapon to create an acid pool as a standard action. This acid pool has a radius of 5 feet per age category of the dragon. When an acid pool is created, anyone inside its area takes an amount of damage equal to the dragon's breath weapon (Reflex half). Any creature that starts its turn touching this pool takes damage, but can make a Reflex save for half. Each round, the total damage dice of the pool is halved until the results would be less than 1d6. The acid pool floats on water, and deals damage to anything on the surface.
Acidic Bite (Su) At old age, a black dragon's bite deals an additional 2d6 points of acid damage. An ancient dragon's damage increases to 4d6, and a great wrym's to 6d6.
Clinging Acid (Su) Acid from the dragon's breath weapon clings to everything it touches. This functions like the acid pool ability, in that the damage dice are halved each round. There is no save for following rounds, however. If a creature made its Reflex save and took half damage from the breath weapon, the damage in all subsequent rounds is halved also. Creatures that avoided the breath weapon's effects entirely are not coated in acid.
Cloud Sight (Ex) - The black dragon can see perfectly through clouds and fogs that normally obscure vision. This includes, but is not limited to, effects such as fog cloud, acid fog, and cloudkill.
Command Reptiles (Sp) Once per day as a standard action the black dragon may command reptiles within a 1 mile radius to come to his aid. The black dragon may affect a number of hd of reptiles equal to twice his own hd. Reptiles with the most hd are affected first. This has no effect on animal companions or humanoid reptiles. This effect lasts for a number of minutes equal to the hd of the black dragon. Creatures under the effect of this ability are immune to the terrifying presence ability of the dragon. There is no saving throw for this ability.
Corrupt Water (Sp) Once per day an adult or older black dragon can stagnate 10 cubic feet of still water, making it foul and unable to support water-breathing life. The ability spoils liquids containing water. Liquid-based magic items (such as potions) and items in a creature's possession must succeed on a Will save (DC equal to the dragon's frightful presence) or become ruined. This ability is equivalent of a 1st-level spell. Its range is equal to that of the dragon's frightful presence.
Corrosive Acid (Su) - Acid damage caused by the black dragon ignores acid resistance and immunity.
Precision (Ex) - The black dragon is amazingly accurate with its attacks. Whenever it makes an attack roll that results in a natural 1 on the die, the attack is not automatically a miss.
Quick Reflexes (Ex) The black dragon is preternaturally quick for its size, and acts twice each round, using two different initiative modifiers (although it rolls only once for initiative). Although it acts twice, it still only counts as one round for the purposes of spell effects, durations, and all other abilities that are based on rounds. The black dragon gains a +20 racial bonus to initiative checks, and its extra initiative count comes at its normal initiative count - 20.
Speak with Reptiles (Sp) A young or older black dragon gains the constant spell-like ability to speak with reptiles. This functions as speak with animals, but only with reptilian animals.
Swamp Stride (Ex) A very young or older black dragon can move through bogs and quicksand without penalty at its normal speed.
Terrifying Presence (Ex) This functions just like frightful presence, but the black dragon may spend one mythic point as a swift action to force creatures in its radius to save again, even if they made their save before.
Water Breathing (Ex) A black dragon can breathe underwater indefinitely and can freely use its Breath weapon, spells, and other abilities while submerged.
Mythic stuff
Ability increases: +4 Str, +2 Cha
Mythic Feats: Combat Expertise (1st rank), Power Attack (3rd rank), Mythic Spells (5th rank), Vital Strike (7th rank)
Mythic Abilities: Clinging Acid, Command Reptiles, Cloud Sight, Fast Healing 5, Corrosive Acid, Quick Reflexes, Precision, Terrifying Presence
Thoughts on this creature? Fully buffed, he's going to be an absolute nightmare to hit. 48 AC naturally, +4 Shield, +6 mage armor (and 50% crit negation), +2 cat's grace, and +9 combat expertise (with no penalty to attack with 1 mythic point spent)...that's a 69 AC!
Finally! With mythic rules, dragons are true threats in single combat.
Yeah, I'm pretty happy with how he turned out. I did notice a few mistakes in my statblock, however, if anybody wants to use it sometime:
1) Should have 4 less natural armor.
2) As Starsunder said, the DR should probably just read DR 20/epic.
3) Caster level for his spell-like abilities should be 24th, not 22nd.