I've been trying to think of things to help you (CJ) with ideas for the components and I think I have come up with a few (of varing quality) -
Spell Sequencer OR combat sensors - What about something like the end of one of your telescopes coming out of a large flat plate (facing 'out' of the picture), with a few mana crystals embeded in the plate (one for each 'level' if for the 'Spell sequencer'?).
Hunter Killer Homunculi - Like a 'squad' of miniture Mephits without wings, with long claws, teeth & spines coning out of their backs and joints. (O.K. that would be difficult but very nice)
Astral Projection engines - well sterotypically Astral projection is where the persons soul/spirit/mind leave the body and travels around. So what about a 'box' with mana crystals (of crude shape/design if on the basic engine) encrusted on it with an Astral cord (the thing that connects the traveller with their body, a silvery translucent glowing umbilical cord) that goes off of the picture or into the distance (either back to the 'Homeworld' or to the Helm whatever seems right to you, well you will only see the cord so it does not really matter).
Gravitic (Astral Flux) Sensors - maybe like the ancient Chinese earthquake detectors, a large urn with 6 or 8 'dragons' around the rim holding a metal sphere (maybe in this case one of your 'patented' mana crystals). The ball was released when the vibrations (in this case in the Astral Flux not the earth) reached the urn releasing only one (the one in the direction of the earthquake) of the very finely balanced balls into the urn.
For the seeders and bays sorry I've drawn a complete blank!
Magic Missile - Well the description says an arrow of magical energy. Personally I prefer a bright pinpoint light with a spherical corona and a trail after it (think pointsource comet). In both cases the idea of larger volleys being made at higher 'levels' appears to be common (so maybe make a Magic Missile V look like a volley of 5 whatevers). For the colour since they are pure mana using the colour of you 'common' mana crystals would be ideal.
Wailing Doom - A disembodied (possibly spectral) non-human mouth screaming
Slay Living - A skeletal hand or a spectral hand, pointing like a traditional weapon with using its index finger. either dark or greenish halos seem appropriate.
Locomotion Disruption - In keeping with the 'Slay Living' idea, what about a spectral hand in a Halt position.
Cobalt Warhead - not sure, but what do you guys think about calling it a Mana Warhead!
I seem to be in a really spectral mood today