Ancient Black Dragon

So, when running the pathfinder campaign, the players found a map of feyblight, and saw a note left on the map during its creation that I had not erased completely.  It was simply a 20, nothing else.  I had used the method of populating the map by dropping dice on it with the CR of the monster/encounters in what locations.  It's a fun way to do maps on the quick, and can help you break through writer's block as you figure out how various ecosystems and political boundaries when you have to explain why there is a camp of vikings hanging out next door to an ancient black dragon.

So anyways, when making the map I determined that the 20 was an ancient black dragon, and fleshed it out to see just how badass they could get.  Naturally, when the players spotted the '20' on the map, they made a b-line there. They were all level 10+ and felt like legit badasses, and they were, but this was the big level boss for when they finished their current questline which I was hoping they'd be at least level 15 for.  It took me three weeks to explain to them how it would be a suicide if they followed through with their plan, they were very determined and only on the day when they were going to finally get there did they fall back.  I actually had to place a bet about how many rounds it would take the dragon to take the party out.

Looking over the notes, I'm left wondering if level 20 encounters are actually any fun at all?  There's a LOT to be keeping track of.  Usually my campaigns wind down around 10-14 ish.

Anyways, here are my notes for Darakna:

The highlighted portions are if it is aware of the approach of the PCs and has time to buff before it strikes.  The bold portions are the spells it's using for said buffs.

The PCs were approaching during winter, and the swamp was mostly iced over, so the dragon's strategy was going to be:

1. Prep: Cast buff spells.
2. Prep area: Cast dimensional anchor on the area. 
3. Surprise attack: Use its breath weapon to dissolve the ice they were walking over so the party would fall into the deep portion of the swamp, getting stuck in the mud with their heads under water.
4. Cast transmute mud to rock to trap party members under water and make things more manageable.
5. Cast darkness 100' and use dragon senses for targeting spells.
6. Destroy the party.

The black dragon Darakna(hobgoblin) AKA Klepisis the eternal gloom(elven)  AKA  Dynythic  the reaper of tears(frost giant), The black rose(dragon), Kastorkir (druid)

Nearby Offspring: Norakna--Dracolisk.

Onrassk -Juvinile black dragon

Korrasin - hatchling in lair

Spells:

Caster level 12 save DC 14+spell level (16+spell level 8 rounds to fully buff)

per day(after buff)

3(3) Level 6 - flesh to stone, mislead(EA)

4(4) level 5- baleful polymorph(usually into beavers, the dragon likes beavers, Fort, will), trans mud to rock, feeblemind(EA)

6(6) level 4- dimension door, dimensional anchor(ray, touch, no save), resiliant sphere(EA), detect scrying(always cast)

7(6) level 3- dispel magic, herosim(+2 attack, save, skills), ray of exhaustion(ray touch, fort for fatigue),   sepia snake sigil(reflex or put in stasis)

7(4) level 2- blur(20% miss), invisibility, eagle splendor(+4 chr), see inv, detect thoughts

7(14RoW)((4)(10RoW) ) level 1- mage armour(+4 touch ac), shield(+4 touch ac, block MM), magic missile(5d4+4), ray enfeeblemen(ray, touch, 1d6+4 str damage, fort half), exp retreat(+30 movement)

at will level 0- dancing lights, det. magic, light, mage hand, mending, message, prest. r. magic, create water.

total buffs: +30 move, +8 touch ac, +2 att, +2 save, +2 skills, see inv, +4 chr.

Feats:

• imp natural weapon bite (bite goes from 2d8 to 4d6)
• wingover(180 turn no move penalty)
• fly by attack (move-standard action-move doesn’t provoke from target)
• greater vital strike (single attack that does 4x dice damage)
• improved initiative (+4 init)Xextra sorcerer spell expanded arcana
• improved vital strike (precursor to gvs)
• multi attack (reduce penalties for full attack)
• power attackXditch for hover
• skill focus stealth (+6 stealth)Xexpanded arcanal
• vital strike (precursor to ivs)
• weapon focus bite Might ditch for improved critical for that 19-20 threat range on the bite attack.

XP 76,800

CE Huge dragon (water)

Init +4; Senses dragon senses; Perception +30

Aura frightful presence (300 ft., DC 25 (27 buff))

DEFENSE

AC 38, touch 8, flat-footed 38 (+30 natural, –2 size)

Buff AC(46, touch 16, flat-footed 46 (+30 natural, -2 size, +4 mage armour, +4 shield)

hp 297 (22d12+154)

Fort +20, Ref +13, Will +18

DR 15/magic; Immune acid, paralysis, sleep, SR 27

OFFENSE

Speed 60 ft., fly 200 ft. (poor), swim 60 ft

buff Speed 90 ft., fly 230 ft. (poor), swim 90 ft.

Melee bite +32 (4d6+16 plus 4d6 acid), 2 claws +31 (2d6+11), 2 wings +29 (1d8+5), tail +29 (2d6+16)

buff Melee bite +34 (4d6+16 plus 4d6 acid), 2 claws +33 (2d6+11), 2 wings +31 (1d8+5), tail +31 (2d6+16)

Charge +36 (16d6+16)-Vital Strike

Space 15 ft.; Reach 10 ft. (15 ft. with bite)

Special Attacks acid pool (50-ft. radius), acidic bite, breath weapon (100-ft. line, DC 28, 20d6 acid), corrupt water, crush

Spell-Like Abilities (CL 22nd)

At will—darkness (100-ft. radius), insect plague, plant growth

STATISTICS

Str 33, Dex 10, Con 25, Int 18, Wis 21, Cha 18(22 buff)

Base Atk +22; CMB +35; CMD 45 (49 vs. trip)

Skills Fly +17, Handle Animal +26, Intimidate +29, Knowledge (arcana) +29, Knowledge (history) +29, Knowledge (geography) +29, Perception +30, Spellcraft +29, Stealth +23, Swim +44

Languages Common, Draconic, Giant, Goblin, Orc

SQ speak with reptiles, swamp stride, water breathing

Feyblight

The Feyblight forest is a large forest bordered on the North by the Iron Mountains and on the East by the Hobgoblin homelands.  During the First Age, it was home to many types of fairies, elves and hobbits, but in the transition to the Second Age was taken over by several dragons, the most powerful being  a black dragon by the names of: The Black Rose aka Darakna(Hobgoblin) aka Klepsis The Eternal Gloom(elven) aka Dynythic The Reaper of Tears(Frost Giant) aka Kastorkir(Druid).

The elves who survived the arrival of Klepsis fled to the west, settling down in a nearby kingdom, where eventually their blood thinned out that there are very few elves remaining in that area, but there is an undercurrent of feyblood in the ruling class of sorcerers that dominate the political scene.  They dream of regaining their ancient homelands, but their feuds with neighbouring city states keeps them from getting powerful enough to do so, though they do have disposable income enough to maintain a very nice city, thanks to their harvesting of a type of acorn on the edges of the Feyblight, which is used for alchemical healing potions.  The groves where these grow are jealously guarded and is the source of many of their wars with neighbouring states.

Very few dare to go very deep into the forest, the bravest will only go until the river Fortuna that leads from the Iron Mountains down to the ocean.  Beyond that, very few return from.

Notable locations in the Feyblight:


Rivers:
There are 4 major rivers that flow from the Iron Mountains down to the sea.  In order from West to East:

Fortuna.  The border where many fear to cross, official start of the Feyblight.

Erav castle.  A castle overlooking the river Fortuna.  The southernmost trading post for the Kingdoms.  There are many hobgoblin mercenaries enforcing the peace in the area and they are tasked with keeping monsters from escaping into the Kingdoms.

Erthorp.  A town north of Erav.  Mercenary rangers serve as guides to those wishing to venture into the Feyblight.  Some of them know the locations of hidden groves of magical acorns.


Shuradb.

Gloomy Marsh, around the fortress of Osmoor, a city that recently ceded from the Hobgoblin Empire, turning away from their gods to worship Darakna, who makes her home in the marsh.

Farthest reaches of the Hobgoblin Empire's zone of control touches the river Shuradb, though they stay well away of the Gloomy Marsh, venturing near only to pay tribute to Darakna.

The source is a glacier where a tribe of frost giants of High Morraine live.

Vetrigoia.  A hobgoblin trading town.  Good relations with Erav castle.  Many of the rangers of Vetrigoia served at Erav Castle when they were younger.

Luga the fallen city.  200 years ago, Darakna destroyed Luga when the Hobgoblin Empire failed to pay an acceptable tribute.  It is now home to monsters, including Darakna's offspring, Norikna, a dracolisk.

Gildaro
Shagrat Hobgoblin fishing village
Goebug Hobgoblin mill town.
Ailderic.  Industrial hub on the western Hobgoblin Empire.
Mercia.  Former elven city, now plagued with bugbears who torture the spirits within.


Eligas
A large river that splits in two, the Hobgoblin's homeland is upon the subcontinent in the delta.  It is considered a holy river, and none may drink its waters except for the Hobgoblins, as they believe it gives them their strength.