I'm looking forward to seeing what you come up with! My Eldar psykers are functioning as a buffer/debuffer in our games, giving the concealing advantages of Tenacity (the Warlock power Conceal), or inflicting a disadvantage such as Untrained (the Farseer power Doom) on the enemy.
My Rune Priest was a little more obvious, shooting lightning from his fingertips like a pro (that is, he has a Light Plasma Launcher) or a battering blizzard of icy shards (Kinetic Pulse Gun).
Magnus