The Invaders come out of nowhere, invading pangea with the goal of overwhelming and dominating the entire continent.  The represent conformity and order, and attempt to control everyone and force uniformity to every individual and species.  In the story they represent oppresion and homogenity, the drive to smother difference or opportunity for uniformity and control.

They come by sea, first invading the orclands.  They have little personality, very little affect, and little in the way of visible leadership; think of a human shaped ant colony.  But they do have spokespeople, a few visible leaders who communicate.  They also have a basic grasp of diplomacy and deception,  allowing them to assure the various species that once they defeat whoever they happen to be fighting now, they will stop afterwards. encouraging a pattern  classic appeasement strategy.  In fact, I'm thinking of the campaign generally reflecting world war two; the humans stay out of it because first the invaders say they only want to conquer part of the orclands, even as they prepare a surprise attack on the human lands.  part of this will be to play the different races against each other; they will stage initial attacks on humans and elves, and blame each other, to inflame tensions between the groups.  It is in one of these strikes that Davis' father and his closest generals/advisors, leaving Davis to take over.  Davis finds proof of the fraud, but has an uphill battle to convince the human authorities, who care little for other races (actively disliking the elves and generally disinterested in the others), and feel confident that the invaders wouldn't dare challenge them. 

After the invaders are defeated, they will retreat back across the ocean, to their unknown and mysterious land.  At the end of the first story they will have returned, beginning their second campaign agains Pangea, testing it's new unity.

Their key to vistory is tremendous numbers, more advanced technology than Pangea, and powerful  magic; the total package.  They more like humans than any of the other races, but not quite; a little stockier, a grayish skin tone, a flat nose only short, nearly transparent hair.

Their advanced technology will be a few anachronistic pieces, less than 20th century, but more effective than pangea; better sailing ships, stronger metals than any but the dwarves, other key innovations.

The invaders are from a continent on the other side of the world, a weeks long journey, through difficult seas; many of thier ships didn't make it, and many died on the journey.  They made the journey because they are overpopulated, and have a belief that they should rule, enforcing control and uniformity across all life; they have already broken or extinguished the few other species in their side of the world, including a third  major continent that they discovered and conquered.

They are very proffesional and very effective with little to no value of individuality, driven by a religius belief that they must conquer and enforce their system.   They represent thoughtless dogma and mindless conquest.  They have no value of human rights, but are skilled enough to pretend, as a tool in psychological warfare.
Role:  Enemy
Story Activities:  The invaders are the overwhelming force on the planet.  Their goal is to transform the world into their vision; unified, universal, bland, gray.  They aren't out to literally eradicate all of their species, but their methods inevitabley wear out the races they occupy.

Of the four continents on the planet, they control theirs, a second they've already cemented unquestionable control over, and a third they've conquered 60% of.  Now they are aiming at Pangea, the last unconquereed territory.  

Their drive is essentially religious in nature; an unquestionable urge to create unity.  They destroy whole cultures and terraform cities and countries to fit their standards.  Their vision is no decorations, little individuation, minimal decorations.  There are individuals and leaders, those with special talents.  They are allowed to take special roles, but no one is really allowed to excel.  This is very important, and a tension within them; they are really committed to the concept of no heroes, no standouts, which holds them back allowing them to win by mass numbers, but leaving little room for innovation.

Their warefare tactics are mostley direct; amass a tremendous force, and overwhelm your enemies.  They do have the capacity for certain basic deceptions, like the fake elvish raid that killed Davis's father, and sneaking in for their second attack, but their best and preffered tactic is direct through any obstacle, rather than go around, or try subtelty.  This is a weakness.

They invade once, tackling one race at a time in the first strike, until they are repelled by the unified force; something that took them totally  by surprise.  They worked with some allies among the races, those who thought they might benefit.  But by and large they had little capacity to cooperate.

In the second approach they are trying a bit of unnatural alliance, working with Davis's sister, to build a secret invasion out of the family estate, working with the  political forces that oppose DreamHaven.  This is a new role, requiring an unnatural subtlety for them.  They will eventually give up, betray their allies, without thinking of it as betrayal, and hit hard and strong, entering the new, second phase of the capaign.  
Character Type: Complex
Motivation:  Uncontrolled