On the topic of counter magics, i was thinking you should at least have to know the spell, to counter it,
So to counter a spell you would have to;
1 identify that it is a spell *weather might change something to ice temperarrally, is that natural or spell enhanced?*
2 invest in finding out what spell it is, If you have that spell to cast very easy fast, if you cast that element but don't have that spell researched slower, if you cant cast the element slower still.
3. invest almost as much in the counter spell as the spell, or define a protection area, smaller, that you use magic to make immune from the spell. (example ice age spell, defining a wall between two lakes, or oceans that hold back the spell, oceans too big to freeze, thin area between them pinches off, so you build a magical wall, the spell stops there.)
what do we think?
Also once you've managed one of thses awesome spells, it's late to end game, if the enemy can't counter, they should be exponetial game enders, ridding across the land on your unstoppable wall of glacial ice. . . type thing.
Overall I like your ideas, except for the part about having to know know a spell in order to counter it. If there are enough spells and enough magic limitations that any channeler is unlikely to learn more than a fraction of them in any one game, it would seriously underpower counter magic and would be frustrating. If someone casts pestilence on my fields and I don't know the pestilence spell and am not able to research it, then there's nothing at all I can do? Sounds bad. Also, countering a spell like pestilence seems like it'd require something very different from the pestilence spell itself. Rather than summoning a horde of insects or plague, I'd want to kill or otherwise remove said nasties - and that could be done in many different ways. I could directly kill them all, I could redirect or send them away, I could make my crops immune, or even make them magically fertile to counteract, but not remove, the pestilence.
I'd love to see some sort of contextual counter magic system, but I don't know how or even if such a thing could be done. In the absence of contextual counter magic, though, I'd rather see a more general counter magic system like the following: countering a spell could have a base cost (which would depend on the magical power of the channeler who casted it, his proficiency in that school/spell, how much mana/essence he put into it, and the spell itself), which would be higher than the cost of the spell itself. However, the cost of countering the spell would go down based on your proficiency in that particular school (or schools) of magic, and maybe even more if you know the spell yourself.
And there should also be preventative protection spells that guard against hostile spells, with a chance of blocking them completely or reducing their effectiveness/duration.
Edit: WHY is quoting so broken?! Usually I only have trouble with multiple quotes from different posts or combining attributed/non-attributed quotes... This time there's just one!