Old Gods Not Gone

I've written before about the two major religions of the continents of Arn and Western Erida in my current campaign world. Both are built on the bones of older religions--most centrally the polytheistic faith of Old Thystara. The "Old Gods" of Thystara were held to be primal beings, older than the universe--not mere Ascended  from a known point in history. The oldest of these Old Gods still worshipped will concern us today.

Here they are, as they're known on the continent of Arn:

Æternus
"The Overlord"; Supreme Ruler of the Gods, God of Just Rulership, Law and an Ordered Cosmos; Shield Against Chaos
Æternus is seen as sanctifying appropriate authority. When even God-King Ahzuran took his thrown, he bowed to the sun symbol of the Overlord atop the staff of the primate of the Æternian church. He's often invoked in the preamble to any solemn oath.
Depiction: A tall, regal man clad in a golden helm and blue armor, with a sun symbol on his chest.
Symbol: A ten-pointed sun emblem on a blue field, or a golden helm.
Clerical Strictures: Clerics in the Overlord's service may wear any kind of armor, but prefer the mace as a weapon. Most go into battle wearing great helms in homage to their deity.

Kaarn
"The Horned One"; The Black Rider, God of Death, War, and Plagues
Kaarn is fundamentally the lord of things that bring death. His bannermen are Terror, Hurt, Dread, and Woe. The call of his hounds is said to cause a wasting disease in those who hear it. He is held to be shunned by the other gods, but is worshipped by humans to appease his godly wrath.
Depiction: A gaunt giant clothed in black. His head is a human skull with blood red stag antlers. Less commonly, he appears as a muscular man in black armor, his face hidden inside a horned helm.
Symbol: An antlered skull, a red right hand, a black battle axe (in his aspect as war god); a black sickle (as lord of death).
Clerical Strictures: Clerics of the Horned One seek to slay foes in battle, and in doing so appease Kaarn and delay the annihilation of humanity. They wear black robes and/or black armor, sometimes with golden, death's head masks.

Illumé
God of Light, Communication, and Inspiration
Illumé is a Promethean figure, symbolizing the bringing of light into the world--both in the literal and figurative senses of illumination. He represents sudden, mystical insight in contrast to Seiptis's hard-won erudition. His flaming sword, Adjaskar, cleaves through lies and veils of misunderstanding.  He is invoked at the beginning of negotiations and at the signing of treaties.
Depiction: A lean, human male with a crown of flames, bearing a flaming sword. It is held to be he who first greeted Ahzuran into the ranks of the gods after his Ascension.
Symbol: a flaming sword, or a flaming crown.
Clerical Strictures: Illumé's clerics see violence as secondary to parley, though they are not pacifists by any means.  They are charged to act as mediators and end conflicts both great and small whereever they can.  Certain monastic orders of his priesthood are also purveyors of psychedelic fungi.

Seiptis
"The Wise"; God of Knowledge and Truth, The Divine Archivist 
Seiptis is a seeker after, and preserver of, knowledge. He also tests the knowledge of others--folklore has it, he forced Ahzuran to submit to a rigorous examination on the fundamental rules of the universe after his Ascension.
Depiction: Seiptis is depicted as a muscular man in a loincloth (like an ancient slave-scribe), with a owl's head, and glowing pupil-less eyes.
Symbol: An owl's head on a white field, or a statuette of an owl in precious metals.
Clerical Strictures: All priests of Seiptis must have some area of scholarly pursuit so that they may serve their god by increasing the knowledge of mankind.