All runes of mage are okay, but Enlightenment is weird one, especially when you compare it to other runes in Chest slot.
It gives 10% more damage when you have more than 70% of mana and 10% of mana regeneration remains while casting when your mana is lower than 30%.
10% boost fells like nothing comparing to 15% persistent critical chance bonus and Fingers of Frost that treats my target as frozen very frequently.
It feels like it must be 30% bonus when > 70% of mana and 70% regeneration while below 30% of mana. Even 100% regeneration while casting is not kind of significant boost, and bonuses of this rune are not persistent, you just deal 10% more damage on first 2-3 casts and get nearly zero mana regeneration when you almost out of mana.
This rune is completely useless, why does it even exists?
This is not a real thing when this rune comes as a tradeoff for 15% chance of critical hit/extra frozen casts