I have personal connection to DoA, because I work as a graphic artist for Dungeons of Aledorn and make this sorts of pictures:
On our Kickstarter campaign (that was a success, take a look here) we had couple of paintings as tiers for our backers.
When picking the topic for my paintings I was driven mostly by my personal preferences as noone was there to bring me into stricts frames ;-) And my absolutely favorite enemy so far is Spectre, an undead creature.
A spectre is ghost-like, yet corporeal, being. One of the most powerful beings of the world, they do not fight personally, they gather army of hosts of lesser undead and are known to even compel Fexts to serve them as personal guards. Masters of the magic from mind and soul school, they also know one elemental school of magic to wreak havoc on their adversaries. If forced to fight they use their claws, they would never use a weapon or shield. Successful attack means curse and loss of level, if you hit level zero, you’ve lost your soul. End of story.
Spectre concept art:
Scetch for the future painting, Spectre with her army of ghosts.
Later I have decide to make it less abstract and paint the fight of the players party with this enemy. Probably it doesn't look as mysthic as it was before, but for sure it is closer to possible situation within the game.
And the painting as it is. Later it will travel to one of the backers unless the decision will be made to create a new one :)