Question about gems in combat...

[Finalgenesis]

There are also cases where a mage who has the gems and capability to cast the given scripted spell but won't.

One example is if the enemy is too "weak" as popular wisdom has it and seem to fit most of the time, but I have yet to figure when exactly AI consider "weak". For example, I've teleported a lone mage into a horde of 200+ troops army and triggered their gem spells, and I've also seen a casting of ghost rider (33 troops + leader) not trigger enemy gem spells. Once you get a feel for it (through many trial and error) you'll get a somewhat accurate feel of when gem spells will be triggered or not.

Also unique cases with spells like reinvigoration, I have never seen my mages cast this spell when scripted under the few circumstances I tried. I HAVE seen opponent cast it once before, I wonder what the trick is to get a mage to cast this spell... Just be careful if you plan to rely on this spell in communions of clutch casters. My gem-trigger sense seem to be fail completely when it comes to trying to cast this spell.

Basically, knowing how to manipulate the AI to do what you want and compensate for the AI's shortcoming is critical. Otherwise seemingly effective scripts will go out of control.