I found that spell in a chest when my conjuration was in the low 30s. It was usable then too, since my high-elf character with an elven helmet of eminent magicka and the gauldur amulet had 300 magicka even then. So my conjuration shot up like a rocket to the current 74.
I don't know that I would call it broken. Conjuration is the one aspect of trying to be a mage that I find enjoyable. Destruction becomes progressively weaker, and I abandoned it after I got out of the low levels. I had every intention of being a powerful altmer mage, but it just didn't work out that way. No fun imo. I don't care at all for how magic works in Skyrim. In Oblivion, you had to be at the right level to use a spell. In Skyrim it just gives you the opportunity to cut the magicka cost in half, and the spells don't level up with you at all, like physical attacks do. It's poorly thought out. But at least conjuration is useful throughout you character's development.
Edit:
You need to be at least level 65 in conjuration for the spell to start showing up...
. . .
Not if you find it in a chest inside a dungeon.
