I had to use it on my priest because I didn't realize I can only have one summon at a time. It was just to respend the one point I spent on the Summon Ghost skill, otherwise everything stayed the same.
Typically, I don't use it. Not for any roleplaying reasons, I'm just not a min/maxer by nature. It's cool it's an option though.
That's right, you can have only 1 summon at the time.
I prefer the Ghost above all other summons. Then I don't really need the Healing spell. But in a previous playthrough I invested in the Ghost and the Undead and switched between them in battle.
For the summons I use the "pause menu" to select this skill and use it. Never put them on the D-pad or the other controller buttons. Why not? Because I'm sometimes to confused and while in battle press the wrong buttons so the summon disappear many times after I just activated it
... With my Creature I do the same: "pause" and select it ... I know it's more "work" ... but it's many more annoying pushing a wrong button so my fresh summonned ally disappeared while the battel just begins
!
That's me
For tactical reasons I like it to do a skill reset, something like Raze mentioned
