well, I think that this explains what I plan to do:
Conchobar spent his time with the elves, taking a great interest in magic and other subjects from them, acting loyal, friendly and as the savior of the elven race should. To all, it seemed as he would lead their race back to the clory that it once was.
The truth was far from that, however. As he aged, he slowly used his magic to worm his way into the minds of the elves, corrupting and subjugating them one at a time without their knowing, he bided his time and gathered his strength, laughing all the while at the elves foolishness.
After years and after they had been sufficently corrupted, he proposed that he would use his necromantic breath to raise their fallen warriors, so that they would have the power to finally retake their homeland. These were all blalant lies of course, but the elves were oblivious as always, not seeing that the undead would be loyal to him and only him. These elves would pay for taking him from his mother, and they would soon know that their many enemies without were much less of a threat than the enemy within...
so yeah, I plan on stealthily brainwashing them, slaughtering those who resist and taking over their last true sanctuary as the center of my domain