Here we go, fast , unfinished sketch, concept art for Kadh + concept arts for Follower (mage UU) and Gremlin.
Sorry i have some problem with hosting, i will try to solve it , atm it will give error when you will try to see real size.
Added: Advisor (UU Archmage) concept sketch.
warning there is some problem with Follower pic, so no real size prewiev aviable.
according units - they can use some of sidar set for sure recolored retextured.
workers - pale skin royal robe sidar workers...
archers - recolored arab archers from this place :
http://forums.civfanatics.com/showthread.php?t=237192
warriors - ottoman warriors from same place , bit recolored
recolor scheme - pale skin , royal (civ color) + black + white wear.
they should not have too much normal units since they getting differenbt units through their plannar gates.
Plannar Gate units:
Gremlin - need to be done , pls someone help

Djinn - exsist
Anomaly - Some glow, recolored mistform or fire ball / fire elemental into blue fire like it for Djinn.
Planewalker - Semi-visible Lawbringer, recolored
Psion - Very powerfull unit, national , limit = 1 , chance to spawn = 0% after 1 spawned. - mind 3 + sorcery + chan 3 = dominate (if gone Mammon path) no hero that way, but once killed , Psion re-appear again (respawn) soon enough.
while for Oghma pass key building allow to build hero.
Key shrine - At late game (Strenght of Will??) Kadh able to chose between Mammon or Oghma path. Unlocked at same tech, and when 1 shrine done - other one is locked and unaviable for whole game. 2 wonders on 1 slot.
Mammon shrine - -2 health, +1 happy with consumption, +20% income in city , +20% production in city , Merchant S free, Sage +2 GP, chance to spawn Psion with plannar gate in city, + 1 happy in city per mind node owned.
Oghma shrine - +2 happy with scholarship, +50% resereach in city, +4 Culture, Sage + 2 GP, build hero unit by completion - base 4 metamagic affinity 2, lvl 3 caster metamagic + enchantment, + 1 happy per metamagic node owned. + 1 metamagic mana
Balance is ok since they are agnostic and have not heroes early at game.
Main hero released on choosing Oghma path - Kadh himself, that go seek himself through Erebus the Knowledge, leaving his mid-plannar heaven, become vulnerable like other men, persuing unselfish, true Oghma champion, needs, should have some crazy spells. Oghma releases him from his plannar ties and send him to experience life as men again , learn and seek the Truth, while being vulnerable like normal Man, Art sketch for unit aviable in this post.
Leader traits losed if killed.