The double rune with intensity and messiness makes good sence to me, all mages should have more mdef imo - this is a good way to make that happen.
Also i would like a the double intensity rune - it could be a rune that was combined with an ability that simultaniously hurt the mage who use it, like a warlock ability (or like pompejs ability, but for mages)
I do not understand why you say that all Mages should have magic defense. Why would they be different from any other kind of hero as far as needing magic defense?
The opinions expressed on this post are my own as a player, not as a Moderator.