Yep, wait until you summon an ice elemental and realizes that it heals crabs for some reason. It will be difficult to make a summoner because I think you need to be rank 2 or 3 to cast level 7 spells or up from there. I haven't played much, but I do have a fire elemental and spider on my earth/fire wiz and an ice elemental on my water/wind wizzy.
I think the armoured skeleton sounds the tankiest, but they are all situational. I know in the Evelyn fight a few of the enemies with fire damage were focused on my fire elemental and given the damage numbers they were doing, I was quite happy they weren't focused on me, of course, they were healing the elemental. You will run into situations like that.