Before anything, I'm new to EnWorlds and I would like to qualify myself as such, as a rookie. A noob.
Even if my opinion is of little value, I do have my own 2 cents regarding counterspelling that I would like to share.
Who knows, it could be useful.
To begin with, Counterspell is overcomplicated.
That alone should keep the DM and players from using it too much, just like Grapple.
But it is as useful as the Trip or Disarm maneuver, if used correctly it can save some sorry arse.
Do it wrong, however, and be ready to swim in a pool of fail, especially if said spellcaster has not taken seriously his Spellcraft skill.
Much like in M:tG, counterspell are made of 4 steps.
1 - Preparing. Prepare yourself in advance. Always. Try readying actions in case of would-be surprises and do research on your spells.
Do not, ever, presume that you do know everything that there is about a spell.
2 - Skill. Spellcraft is your friend. The DM has no obligation of saying "and he cast ston skin". Use it and abuse it.
3 - The spell. To counterspell you need a spell. Duh. Just like on M:tG, but you can use the same spell effectively or a Dispel Magic.
4 - Oportunity. Do not, I repeat, DO NOT dispel the Magic Missile. Use it wisely, but never waste the oportunity to bend your foe over.
One nice example of counterspelling goodness is to save that lonely slot of 3rd level your 5th level mage get with a Dispel Magic, instead of the classic Fireball (a 5d6 damage spell isn't the most useful trick someone can cast, anyway).
Now your party is obviously gonna find some devious evil caster sooner or later and they don't have to be 5th level. It could well be a 7th, maybe 8th, level NPC and 4th levels spells include some really troubling ones, like Stone Skin.
Now, what can you do against a so powerful spellcaster? Well, your wizard can't do that much damage, and he probably has any sorts of elemental protections.
Then why don't you try the Fighter? Every good spellcaster knows that the fighter is the BEST spell ever cast. He does the hackyslashy job, carry your stuff, takes no slot of any level, take your damage for you and you still earn some XP from it! But beware, a weak Will save will get the fighter out of ranks pretty quickly against persuasive magical enemies.
Enters the Counterspeller!
In a fair fight were both wizards are getting low on magical resources, just ONE successful counterspell on that Hold Person, Invisibility or Fly spell can make said enemy writhe in agony and despair.
Why?
1. He lost a turn doing NOTHING. What pretty much is a death sentence when you are talking wizards;
2. Now the fighter can safely hack and slash his bottom into oblivion;
3. You prepared in advance. You readied an action, indentified his spell, used YOUR spell to counter his and won. You basically bitchslapped his magical face.
Now, how could it turn the wrong way? Use the slot for a Fireball instead of a Dispel Magic and you are pretty much doing it wrong.
Even as complicated as it can be, I can't actually fathom why someone wouldn't love to work a counterspell now and then.
It's like a fighter that only hit things and never Trip or Grapple or Disarm , it's pretty much a sorry sack of potatoes with a sword.
Wizards are full of resources, but players should explore then MORE.
I would love to meet someone who actually knows all the uses for the spellcraft skill, or which spells one can cast while swiming/climbing, etc.
You never know where there is power, use all.
That is, in my humble opinion of course. I would like to hear other thoughts on the matter.
PS: Remember to ALWAYS ask your DM a spellcraft check when your character is casting spells. Because, ironically, an enemy that doesn't know you cast a Dispel Magic on his previously cast Fly spell will still try to jump from the roof and save himself.