Lucent Sphere - Fire an orb of light forward from the caster that takes 1 second to arm. Deals minor single-target damage, but is somewhat spammable. Lucent Spheres will detonate if they strike the caster. dealing area damage and refunding their energy cost. (The orb moves too fast for you to normally catch up with it, but certain abilities will make this possible. See below.)
Flash Forward - The caster dissolves into light waves and fires himself near-instantly to the target point. Enemy units along his path receive damage. Can also be used to detonate Lucent Spheres.
Mirage - Swap places with the target for 5 seconds. When the effect ends, swap again (if the target is still alive).
Refraction - Fire a beam of light that bounces between targets and slows them briefly (chain lightning). Subsequent targets take less damage, but are slowed more.
Diffusion -
(Passive) Gather left-over energy from spells cast nearby in the form of charges. You'll glow brighter for every charge.
(Active) Release all stored charges in an area around the caster, dealing damage per charge. Damage decreases with distance from the caster.
The idea here is to create a very opportunistic type of caster. He'll generally prefer to stay out of the fray and has a few tools to accomplish that, but he's also very good at taking advantage of chaotic situations. Mirage in particular is great for this, even if it doesn't do any damage by itself. There's also some interplay between abilities, but they can still be effective on their own so it should fit the "purchase" model.
@Fullachain: Go
I was thinking a spiffed up version of the High Templar model. You could probably get away with using a Probe or something, though.
Feel free to pick it apart and use it however you please :)
Photomancer
(Passive) Gather left-over energy from spells cast nearby in the form of charges. You'll glow brighter for every charge.
(Active) Release all stored charges in an area around the caster, dealing damage per charge. Damage decreases with distance from the caster.
The idea here is to create a very opportunistic type of caster. He'll generally prefer to stay out of the fray and has a few tools to accomplish that, but he's also very good at taking advantage of chaotic situations. Mirage in particular is great for this, even if it doesn't do any damage by itself. There's also some interplay between abilities, but they can still be effective on their own so it should fit the "purchase" model.