I will give some more varied creature ideas now that I have extrapolated on so many draconic imaginings.
Griffons that live up in the mountains, noble creatures, usually keep to themselves. May be quests to help the griffons fight off a young wyrmling that is aggresively expanding into their territory.
Trolls, trolls are a must in hills, foot hills, caves, and forests. Usually your average trolls has a weakness to fire and a slim regenerative ability. Tribes and armies of trolls can be led by either a Troll Lord and or a Witch Doctor. A witch doctor is an elder troll that can channel low or mid-level earth spells, while a Troll Lord is a massive Cave troll, with immunities to poison and paralysis, and massive health regeneration. Only tru weakness would be fire damage.
Needless to say, woods trolls are more likely ruled by a shaman/ witch doctor, and cavernous trolls are more likely to be led by a Troll Lord.
I think the deserts should be roamed by tribes of wild, halfling "sand-men" who live in social symbiosis with the Giant Scorpions. The scorpions and the sand men are scattered throughout the deserts, although a large density of them gather around the Lair of a Sphinx, which is a large Half-Lion spell caster that can channel sun mana. In addition, Sphynx's are quite large, nearly as large as a dragon even if not half as powerful. Still, Sphinx's are generally the most powerful thing in the desert unless you are facing an Ancient Blue dragon, or perhaps a Bronze or Onyx dragon (onyx is a possible rocky/desert dragon with abilities of earth, which is some-what missing in my current Draconic species diagram)
ANYWAYS, Sphynx's can grow to be as powerful as nearly a Large dragon (couple steps below legendary) and the lair of a Sphynx is an epic lair in the desert, mainly due to the paralytic and poison abilities of the Scorpions and sand-men, whom follow a Sphynx in a massive following.
If its a living lair, the Sphynx's troops will wager to take over the entire desert, and gain more troops by converting rogue tribes of Scorpio-Sandmen over to the cause.
There are also forest witches and swamp witches. Swamp witches can wield legions of Giant Swamp Snakes, while forest witches can summon elder treants to their aid. Also, if you expand into forest, occasionally a treant could go bezerk and attack you. This could perhaps be limited to certain areas of thick forest and "wild woods"
In various areas, hill giants will be prevalent, perhaps actually will by Cyclops. Largely immune to magic types, a Cyclops will have to be taken down with martial might, and perhaps a bit of trickery. Cyclops can attack multiple units in front of it, although has a massive penalty to being attacked from behind. Also, is weak to marksman arrow shots (especially if somehow aimed for the eye/ the head)
Centaurs will be brutish and bestial bandits, trampling over plains and light forests.
In addition, light/mid cover forests and groves will be prowled by the vicious and tricky satyr's and forest pixies. The satyr's can use music to place units to sleep, or paralysation, or charm, and forest pixies are flesh-eating fairies of doom, having low health/defense, but extremely high DPS melee, extremely good at hiding in forest and laying ambushes. A unit paralyzed by a Satyr can become pixie food fairly quickly.
In lakes and grottos, perhaps hidden bays and coastal areas, powerful naga will await in the depths, for ye who wanders here. Ordo-Naga are simply large lumbering snake-men, with thick skulls and thicker skin. Low intelligence and even weaker formation, although if caught unawares, you unit could be shredded by the Ordo-Naga.
Much more rare, and much more deadly, are the Vishi-Naga. Not every Naga lair will have vishi naga ... maybe 1 in 10 naga encounters will encounter Vishi-Naga. They are powerful spell-casters, and can channel several different types of mana ... something most beast channelers are unable to do. Most common spheres Vishi-Naga will be seen casting are Water, Air, and Lighting. Although Ice magic has been known to be cast from certain well learned Vishi-Naga. The most powerful sometimes can channel life and death. Although, to see a death casting Vishi-naga would probably be 1 in 100 odds for each Naga encounter, or more accurately 1 in 10 odds for each Vishi-Naga encounter.
Vishi Naga are usually more slender, with high magical resistance ... while Ordo-Naga have nothing but brute strength and a massive amount of physical defense/deflection. Archer units are ineffective against Ordo-Naga ... except for extremely skilled marksmen able to penetrate the rare weakpoints consistently.
Most giant spiders start out as a basic type of spider, hiding within a wooded lair. Or perhaps roaming the plains if particularly aggresive, or pushed out by some other beastie. Past 5th level though (at 5th level?) the Spider can choose to evolve into something more .... Wether a stealthy Desert Spider, who hides under the sand in his burrows for unwary passerby, the Bezerker Spider, who usually openly roams the country side in search of bandits or caravans to feast on and to feed a growing nomadic brood. Or the crafty jungle-spider, who waits high in the trees with intricately traps set below. This one typically has an unchanging lair, and its many young have first dibs to feed upon prey that stubles into the poisonous trap of death.
Another possibility is the lone aquatic spider. He may choose to live at the bottom of a Murky swamp, or make it out to see, and live off of fish and small naval-craft that wanders by. This type of spider is the most dramatically evolved spider, and is never quite as effective on land, unless right next to a watery source. The advantages of a watery spider are that its poison has evolved into a form of ice magic, and slowly freezes its victims. Also, it is immune to Water and Ice mana, and has no magical weaknesses. (most spiders have either ice, or fire weakness). The one true weakness of an aquatic spider is they almost always live alone, and Always hunt by themselves. However some-times they are hired by greater powers, with magical or otherwise power over them, and certain water-lords can be found using aquatic spiders in their armies.
