Gregorius first tries to check the local aura once more.
[Non-fatiguing, loud words and gestures to give casting total of 14 + Aura, against a base level 3. He'll try both magic and faerie, in case there's one aura overlying another.]
He then spends a few minutes inspecting the cube carefully, looking for any maker's marks, other identifying features, or just anything else of interest.
Next, assuming he's not in a strong faerie aura (in which case he's nervous about botches), he tries to work out the amount of spun vis present in the device, followed by the arts it's aligned to.
[Variants of Scales of the Magical Weight and Sense the Nature of vis, designed for enchanted items rather than spells/raw vis. Both InVi 5 (I think I can get away with Individual rather than Group target for the latter, as he's casting it on an individual object, and Ind Vim spells tend to either affect every spell on a single person/object, or a single spell. It's slightly iffy, though, as I'm making an analogy for vis.
Casting scores are (In 6 + Vi 5 + Sta 1 + Aura ? + die 2 (invisiblecastle.com/roller/view/3348023/)) /2 = 7 + Aura/2, should work.
(In 6 + Vi 5 + Sta 1 + Aura ? + die 5 (invisiblecastle.com/roller/view/3348024/)) /2 = 8.5 + Aura/2. Again, should work.
My understanding is that he'd have to spend a season investigating the device in the lab to really answer for definite questions like "how is it triggered", although he could work out a certain amount, such as the magnitude and effects, if his InVi total was high enough.
Magic Theory roll is Int 1 + MT 4 + die 7 (invisiblecastle.com/roller/view/3348044/) = 12]