Orcs

The beings known as elementals have long perplexed scholars. What drives soulless matter to rise in such imitation of life? Particularly baffling are those elementals that seem to defy the categories of matter discerned by the great sages. A being all of earth or fire may be strange to behold, but its nature is at least clear--but what of a creature of ice, or lightning, or salt?

For as long as humans have lived, they have fought with each other. Philosophers and poets have dreamed of worlds without war, yet no matter how many such dreams they spin, those worlds scarcely seem any closer. Jesters and jaded minds say that as earth and water are basic building blocks of matter, so is war a basic building block of humanity. If you need proof, they say, just look at an orc.

Sometimes, when a great battle has ended, the hatred, rage, and pain of the fallen does not pass from the world. From blood-soaked mud, mangled flesh, sundered arms and armor, it crafts new bodies. They have no eyes--they need none but their helmet-slits. They have no tongues--no words are left to them, only howls of hate for all that is not an orc. Their wrists end in blades, barbs, and bludgeons--they no longer have any other use for hands.

They know neither pain nor fear. They do not tire. Though they hunger, they never starve. The warband marches, unceasing, ever in search of the enemy--and to an orc, everything that isn't an orc is the enemy. Bloodthirsty army or defenseless village, it matters not as long as there is killing to do. Their bodies, though awful to behold, are ideal for the task, stronger than all but the mightiest warriors. With every "victory," they grow stronger, carnage and metal rising to replenish the ranks. Unchecked, the warband becomes a horde, villages becoming cities and empires.

The most terrifying thing about them, though, is that they can be used. Soldiers follow orders. With the proper magics, or sometimes just the charisma and bloodthirst of a sufficiently cruel warlord, they transform from an untamed force of destruction into a weapon of horrifying power. They become capable of scouting, retreat, ambush, and siege. Their hatred will not be checked, though, carrying out all orders in the most brutal way possible, sparing none unless commanded to take prisoners by name. A warlord who tries too hard to bring them to heel may suddenly find themselves the target of their own "loyal" troops.

They are best fought with a small, elite force. Attrition is ever on their side--the horde always hungers.