They call it a Rune.
I'm not sure what this whole discussion is about. It started out with the question "is magic underpowered?" and ended up with some arguing that it doesn't even require "skill" to play a Conjurer. I guess we know our answer, eh?
At this point, I'm beginning to think that the "skill" that's being referred to by some in this thread is the player skill of moving a mouse or thumb-controls, and not the 18 skills our characters have to work from.
For what it's worth, one of my long-term characters in Skyrim is a relatively "pure" Conjurer khajiit. Jo'Nissa wears no armor, nor any enchanted robes. She wears ordinary clothes while in town, and nothing but a magic-boosting ring, an amulet of Arkay, and the Aetherial Crown while hunting. She uses a Bound Bow and an Atronach (either fire or frost) when fighting. Her fall-back weapon when cornered is her "claws."
There are times when she will throw an atronach into a room full of enemies, and let it thin them out. Other times, she will crouch in a hidden place and snipe enemies with her bow. Sometimes both.
The thing is that you can't cast when you're holding a bound bow. So if your atronach bites the dust (which happens a lot) you have to quickly decide whether to sheath your bow to recast the summon, or to try to manage on your own bow skill. A lot of bosses have charged Jo'Nissa, taking arrows all the way, and have collapsed at her feet. It's a dangerous play-style. Sometimes she has to run away.
I guess it's not the same as the cowardly Conjurer being discussed above, who needs no skill to play.