I know i'm not the GM and this is probably If I could suggest maybe instead of exactly like 3 eye its like a 3 eye plus? Like not only does it temp open up the magical sight but temp gives them access to raw magical talent like nothing complicated but classical evocations stuff ( fire, force, frost, ect. ) but given their lack of knowledge and information, they don't know the steps to protect thier minds from the magical back lash of using magic ( not to mention that natural mental damage that happens with having unrestrianed sight open ) so they could be highly addicted, highly unstable, and highly dangerous mo-fo's.

Given the big "K"s level of power and skill I feel like it being something far more potent and dangerious than 3 eye was would make some sense, especially if it was intended to be a war tool.

-edit- 

ah never mind the DM has spoken, though something like ^ could be a good idea to throw around for a background or side plot.