You're absolutely right. It works, but it's a whopping 30 mana and requires lvl 3 Distortion magic, which the fighter classes can't afford so easily in the beginning. As a mage, you won't have much trouble.
Bone Dragons provide greater efficiency, because even a lvl 1 Evlin for 15 mana (1/10 of the stack recovered) can save you from getting any losses. Lvl 2 is 25 mana and replenishes 1/5 of the stack, while for a fighter class Time Back is 30 and is a one-time miracle until you manage to save up 30 mana again (mana accelerator works, but why spending it on recovering mana when you can spend it on something offensive).
That's the thing... KBTL and KBAP are games that really like efficiency
