Frankly, I would just disable all summon spells until they patch them in a few months or years when they feel a worthy sale is on the horizon.
I was thinking about going back to 2.4... - the only notable probable improvement that I am aware of is that the multithreading appears less buggy - I used to change processor affinity but it doesnt seem to help any more in 2.5.1. My gameplay experience does not agree with their "months of fixes, performance optimizations, AI enhancements, balance tweaks and a host of other improvements" claim.
Edit: If they would actually bother to list their "fixes", "optimizations", "enhancements" and "improvements" it would be
more comprehensible and also help people with modding.
That should work, to some extent. Expect some hanging issues when there's multiple casters, multiple summons, or too many units around the target. <snip / relocate to further down>
Unfortunately for my "hardcore no reload unless crash/bug/hang" play style an unlucky roll could be a game ender for sth like Wildling riders - so not my thing.
I had some other "really good" ideas which didnt work at all:
1) use tactical autocast on the summoned monster to kill other versions of itself - tactical autocast isnt used when summoning sth unfortunately, this probably also means that the Fear effect on summoned Delin is wasted I think
2) do damage to all but one of the summons upon summoning them (like Earth Elemental) - problem is that the summons inside the spell in which they are summoned appear to be excluded from the damages from that spell no matter how I order stuff in the .xml
If it would be possible to immediately somehow chain two spell casts onto the same target into the same AI action it may be possible with creative scripting but I dont see a way to do that either.
Adding a summon spell blocker on the target after one cast might reduce the hanging issues.
Whats a "summon spell blocker"?
And isnt the problem that the AI targets an enemy unit independently of it being allowed to do so or it making sense? At least thats my impression: The AI picks an enemy unit as spell target no matter what the .xml code says - it seems to just ignore the .xml code for the targeting purpose. Except for ~10% of the cases that it actually does pick an empty tile.