Pure mage has been a lot of fun for me. I started mainly relying on my follower Lydia to do the melee combat, distract the enemies and I would stand afar and cast fire or ice spells. Soon, I had the Impact perk and that really made things progress. I still needed a follower to destract the enemies, but I was able to handle more enemies by casting a dual-wield fire or ice to each attacker so that enemies spent most of their time recovering from being stunned. Always used the best available Mage-Armor (Iron, Ebony, etc).
But as I learned Conjuration, I quickly became a 100 master, and can create one ot two Demora Lords to fight enemies while I stand back and cast desctruction spells from afar.
But my Alteration and Conjuration skills quickly went to 100, but my Restoration and Destruction Lagged. So once I achieved DragonHide, I now dual cast Dragon-Hide, go alone, don't summon a Lord unless necessary, and do all the damage myself. Use a high-power destruction spell in one hand and the Greater-Ward in the other. Now my Destruction and REstoration are catching up.
I lately mastered Enchanting, but didn't have any of the perks. I used up all my saved perks to be able to cast dual skill enchantments. With a ring and an amulet each having +50 magika / 20% less for desctruction spell, I can now cast expert->master level destruction.
I recently learned that the Ancient Dragon is still very difficult to kill at times. Just this morning I had to call my ol' buddy dragon to help with an Ancient Dragon. In this fight I learned that Dragon-Hide and Dual-Weild Greater Ward will result in no health loss when taking full spray from an Ancient Dragon. But you better keep running, because a greater ward will not help against his Bite!
It's been a fun progression.