I've noticed this several times by now: there is some problem with the tactical version of summon air elemental.
The automatic 9*9 gust of Wind has several flaws, especially happenning on small and/or crowded maps with some impasssable terrain.
The direction toward which ennemy units are pushed back seems quite random and has caused the following problem in several of my games:
* Sometimes the units are actually attracted to the tile where the summon spawns. This has the following consequences:
- either the elemental does NOT spawn (but the mana is expanded and the surrounding units disabled unless they resist)
- either the Elemental DOES spawn... on top of an ennemy unit (same tile).
The first case is a bit cheesy; the second just seems weird.
Either case looks rather unpolished... and it is sometimes quite annoying to not be able to predict which way the ennemy will be pushed 
Thanks for all.