Must be meaningul. Considering that the cover must be forced to be eye candy for the lazy (or so it seems), it should be "interesting" and informative. Avoid lies.
Keys of Elemental:
- Land revival (life/death)
- Conflict of viewpoint/interests (Men/Fallen, Life/Death)
- World shaking magics
Could be more, could be less, but in any case we cannot have zounds of them. No space on the cover!!!
"Defending the Fire Shard"
Upper right of the picture we have a stone stair in what appears to be an old and ruined temple that lead to a Fire Shard. Drawing energy from it, we have a human Sovereign feeling wild (Fire Shard + Feeling Wild = guess what I mean). To each side he has a couple of warrior with different crests. In front of them, a line of bloodied soliders holding the line.
Lower left of the picture, a Fallen Sovereign leads a horde of fallen beasts while preparing his own spell (I'd say ice to increase the opposition feeling between both factions).
Both groups should have different colour schemes (white for human, based on Altar, and black for fallen because humans got white).
"Two sides of the same coin"
The picture is of the upper half of a Sovereign, like a portrait, that is holding a fragment of a Water Shard on his hands. In the background we can see the lands, a couple of castlee to each side as well as a couple of armies facing each other.
The right half of the picture presents the men (with their green plains and all) while the left half of it presents the fallen (lava terrain and all). This division affects the sovereign too, the right half being a human and the left one being a fallen. Both parts of the sovereign should be more or less simetraical but doesn't prevent the fallen to have extra eyes, fangs, stone skin, spikes...
(Problem could be some people expecting to be able to change sides during play... which some will do anyway, cover or not)
An adventurer (or two, but not a whole group for space reasons) watches from a cliff, all from a third person view.
Under the cliff we can see the lands of the men meeting those of the fallen. In that landscape, two armies fight each other (men against fallen, obviously) while above them a couple of dragons are gutted by the other (Dragon Blood Rain!!! And other... stuff rain too. Ok, let's ignore this last bit.).
Add some falshy lighting/flames in the ground where the sovereigns are trying to make the enemy to feel uncomfortable (and dead).
The "Not going to happen (and be glad about it)"
A female warrior as beautiful as possible with good "attributes" and wearing a micro chainmail bikini that barely covers the "naughty bits" fights against a big man with more muscles than one can count that wields a very big frakking sword, dresses a bear pelt and is covered in bright tattoos. The man leads a horde mixed of undead creatures and weird looking tentacled beasts while the female warrior leads a coallition of channelers blasting their way through enemy lines with magic, amazons as less dressed as possible (some myth about men/fallen warriors getting distracted by female nudity) and some rune covered golems.
The "No cover" option (also known as "Not going to happen (and be glad about it) Part 2")
Basic edition comes in a small chest where you can find the game disk and manual. It includes a small hammer and chisel so players can carve any "cover" of their liking on the game's chest.
The "Prince" way
Except for the compulsory ESRB and other marks needed (included system reqs in the back), totally black box without markings or text. Just a simple Symbol.
Just let Matt Groening draw the cover. Similarities with characters from The Simpsons and Futurama are encouraged. Let then people suppose things based on the cover.
The Way of the Cosplayer
The Stardock crew represents a scene from the game doing cosplay. Brad can appear as a Sovereign (a pity I don't have my "Brad Wardhell" pic here!) casting a Summon Bee Swarm over the enemy Sovereign (BoogieBac maybe?).
*ducks under heavy cover*