I know it's possible to disable DV completely, so I believe making a mod banning Instant Travel would not be a problem.
I think that it's the factor which makes AI think for ages on some bigger maps. It multiplies possible paths for AI to calculate and often allows to jump to totally different zone.
Some tests seem to confirm it.
Also, it's some kind of unbalnce and breaks random map structure completely.
You can also change the mana that is needed to cast the spell. In my games it cost 200 mana to cast it. The AI can still use it but not so often.
It seems to me to be a rather good compromise.
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