Manifestation works on spike spells now. It surprised me too. I don't remember it ever being announced in an update. An LS member told me he noticed it working, then I tried it and was surprised myself. I know it didn't work originally. Maybe it was updated when SCH got the spell natively (December?) Wiki even lists spikes as manifestationable now.

As far as the ability wording, I don't think it lists dark magic either but Klimaform, Stun, Aspir, Drain, etc...

It's funny when you cast it too. Unlike every other AOE spell, there is no animation on anyone other than the caster. The log just says they received the effect and it works on them.