Quick and dirty while on break at work
Nos`rahiim
Wyverns of the Lingering Rot
Undead Large Dragon
Hit Dice: 8d12 (52 hp)
Initiative: +1
Speed: 20 ft. (4 squares), fly 60 ft. (poor)
Armor Class: 18 (–1 size, +1 Dex, +8 natural), touch 10, flat-footed 17
Base Attack/Grapple: +7/+15
Attack: Sting +10 melee (1d6+4 plus poison) or talon +10 melee (2d6+4) or bite +10 melee (2d8+4)
Full Attack: Sting +10 melee (1d6+4 plus poison) and bite +8 melee (2d8+4) and 2 wings +8 melee (1d8+2) and 2 talons +8 melee (2d6+4)
Space/Reach: 10 ft./5 ft.
Special Attacks: Breath weapon, improved grab, poison
Special Qualities: Undead traits, Darkvision 60 ft., low-light vision.
Saves: Fort +7, Ref +6, Will +6
Abilities: Str 19, Dex 12, Con 0, Int 6, Wis 12, Cha 9
Skills: Hide +7, Listen +13, Move Silently +11, Spot +16
Feats: Ability Focus (poison), Alertness, Flyby Attack, MultiattackB
Environment: Warm hills
Organization: Solitary or flight (3–6)
Challenge Rating: 8
Treasure: Standard
Alignment: Usually neutral
Advancement: 9–12 HD (Huge); 13–21 HD (Gargantuan)
Level Adjustment: —
A wyvern’s body is 15 feet long, and dark gray; half that length is tail. Its wingspan is about 20 feet. A wyvern weighs about one ton.
Wyverns speak Draconic, but usually don’t bother with anything more elaborate than a loud hiss or a deep-throated growl much like that of a bull alligator.
COMBAT
Wyverns are rather stupid but always aggressive: They attack nearly anything that isn’t obviously more powerful than themselves. A wyvern dives from the air, snatching the opponent with its talons and stinging it to death. A wyvern can slash with its talons only when making a flyby attack.
Breath Weapon (Su): The Nos`rahiim’s breaths a cone of green gas that has the smell of rotting earth and corpses. Anyone caught within its effects will find their eyes watering, their stomachs nauseated and an overall feeling of being unclean. However, just as their sting seeks to rot the flesh from a person’s bones, their breath rots away everything else, inflicting 8D6 points of damage to objects, equipment, and weapons. The Reflex save DC against a breath weapon is 10 + 1/2 wyvern’s HD.
Improved Grab (Ex): To use this ability, a wyvern must hit with its talons. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it wins the grapple check, it establishes a hold and stings.
Poison (Ex): Flesh Rot, Fortitude DC 17, initial damage 2d6 rounds of bleeding (1 point on round 1, 2 on round 2, 4 on round 3, etc as the flesh rots from the poison) secondary damage 2d6 Con (from rot spreading to internal organs). The save DC is Constitution-based. Bleeding will continue at its last amount, up to the required number of rounds, once the poison has been neutralized. A cure spell will stop this bleeding, but only if it cures at least as much as damage being taken per round. Only spells that restore flesh can heal the damage caused by this rotting.
Skills: Wyverns have a +3 racial bonus on Spot checks.
I figure this might be a basic start - 15 minutes is not enough time to flesh out everything I needed to, plus a lot depends on campaign background.