[Daisuke]

If youkai get an increase in maintenance, I would suggest adding a skill along the lines of "increase your FP by X for every youkai you have out" and making summon storm summon youkai randomly within a general range instead of anywhere on the map. This way you give summon storm a bit more reliability to make up for the AI and the whole "I can move twice for several turns and drain all your FP and your Youkai will probably spawn on the opposite side of the map anyway".

This would create a noticeable difference between a full summoner and Mages that summon youkai while casting their normal magic since having high level Youkai with summon storm would basically mean "Maintain this or your FP is gonna run dry in a few turns" and there would be no way you could maintain 6 youkai on top of casting mini nukes.
This also makes silence useful against a summoner (did I mention silent prayer needs to be a changed a bit? maybe having a long cooldown but instead of curing silence it could prevent silence for a few turns) and would add a bit more of a counter to them since they get a large defensive buff from astral aegis.