well, I thought it milled only one card, so you could control the damage with RT.
To make sure the mill is balanced I'd think of how many bolts/quanta do you need to kill with fire and ice and make sure its not enough to deckout with this quantity. The problem is that this is in-element with inno and that milling reduces the options your opponent has to answer.
I'd rather see this with a fixed low quantity for milling and scale the damage appropriately.
For the cost consider that a one card mill makes this plus RT an instakill + added effects.
I really want to keep the milling a scalable thing. It makes it stand out from other cards.
Maybe the damage could equal the cost of the first card discarded then just add 1 for each additional card.
Two card single insta-kills are already in game viz freeze+shockwave, and unsummon + burn card / inno.
The only tricky thing here is that this is in-element with its combo pair.
Right now, innovate can provide an effective 3 card mill, plus more with the rico combo. This spell doesn't target so rico will not be a problem.
Given that this is purely offensive, it should be reasonable to have it slightly more effective as a mill... A cap of 5 or 6 milling is probably about right then...
99 / 6 is roughly 15 to 16 so that will be the mill increment count I guess... The cost can then be 6 / 4.
So the unupped can pull off a single card mill at 99
, while the upped version can pull off a double tap with 98 or 99
Lastly, at a cap of 5 and 6, the most that this can mill is 30 / 36. With 6 innovates as well, that pushes the threshold to 48 / 54...
So the upgraded version with a full complement of this and innovate can pull off a standalone deckout... provided that the innovates operate optimally.