If flameburst and other black op's are so powerfully, why not increase the costs of those. Especially when you look at flameburst it is a very cheap spell and at right time it does alot of damage to kindgom. Have a good look at cost of power farsight compare to flameburst. Really if a player wants to be a mager, they you should pay the price to cast these spells.
Increasing the cost on FB is exactly what I was going to suggest and It's simple.
With regards to everything else. At first I was sort of against an overhaul due to concerns of balancing. This mana burn concept is very restrictive to magers ; so really it is a nerf to the maging system. As long as there is a way to offset this nerf and everything is balanced out, then I am all for the idea, as I see much potential. It adds more complications, challenges, and choices of being a mage.
I do not like the idea of giving free spells away though. Dust is there for a reason and if Power FS and lesser FS are freely available then that takes away from KD's that would like to conceal them selves. Make people use dust regardless- it's what towers are for.
The reason I like some of Quaffle's/Strikers ideas here is they bring depth to the game. I will say "wow" to the amount of effort and thought that obviously went into this.
Fergy's additional idea would be a double whammy to the maging system. I think it would be too much to add a "mana burn" as well as a spell accuracy decrease to a system that already requires dust and mage power. That's four layers of obstacles that a mage has to get through and we haven't even gotten to spires yet, which is a whole other issue LOL.
So like I said, I would be supportive of something like this if we could add something to counter the nerf to the maging system. I really like Quatro's idea for a silence spell too, although it is another challenge that a mage would have to face.
Perhaps the introduction of a "spirit" stat to the ruler, which would give a slight boost to the mage power and mana burn
by some amount as determined by the amount of points applied. The bonus could be effected the same way, as current requiring the Ruler to be at home (or if he is away at the targets location). This would help those that choose to be magers have less restrictions and perhaps help deal in some way with KD's that late in the round feel like converting to a realm support role. This way, as the ruler grows they have more predefined roles and add their points as they go and cannot suddenly switch when they recognize that they are not as in good position rank wise (I am only talking a slight boost as determined by the amount of spirit points applied and not enough to completely alter the way the game is currently played) Perhaps they could add a bit of spire reflection too (a small amount).
So as to not derail this topic, I will post more on Ruler Stat ideas in the Suggestions forum and then post a link here.