ToME: the Tales of Maj'Eyal

Rather awesomely, A mage can use a mana surge ruin to increase his base rate of mana regeneration by 600% So upon using another mana surge ruin at the same time, and discovering that this base rate which has been increased by 600%, then gets increased by another 600% ( (base rate x 6) x 6), you have a mage which regenerates all his mana every turn.

Not sure if this is intended, or just overlooked code But it does make a mage rather god like D;

I always assumed it was intended behavior, though I agree that there's no guarantee that's the case. Also works with Manaflow (though you have to activate Manaflow *first* and then Manasurge). The way things currently are, yes, archmages CAN get large quantities of mana all at once, but at the cost of rune slots. If intended (or not unintended, at least), then it's a bit of a trade-off. Either you can choose to have an emergency escape plan in the form of, say, another Shielding rune, or you can choose to double-up on Manasurge during emergencies and hope you can blast your way out before the 10 turns run out.

Funny thing is, even with 2 low-cooldown Manasurge runes and Manaflow, there are still times when I've run out of mana.

I believe most mages (ab)use this, and it's known. Whether it was intended from the start? Dunno, but it's a valid tactic and not frowned upon in the slightest ways.