Somebody has been going through their card collection. To keep a little more true to the card, could it make knights deal counterattack dmg *before* attacking enemies damage it? This might be hard to add in, but it would mean almost dead enemies won't attack it unless they want to die without doing damage.
And for enchantment mechanism i thought a magical item that you can place near the battlefield that has a eg. 8 tile aura giving this eg. First strike.
Placing: a conjurer unit can spawn it there with either a big cooldown, or without cooldown but making these magical items "legendary" so you can not own more than one at a time.
Make 2 versions. One that gives an aura for it, but requires spell upgrades to be enabled. The other to be either an upgrade to an existing unit, placed on a new unit, or a single target enchantment you can cast on your allies.
I was thinking it might not be balanced at the start cause pikemen were going to die without the chance to act as a counter but since most of anti cavalry have now range 2 is viable, also elven warriors can dodge counters with 80% chance after techs. The only problem is for undead spearmen but we are putting in phantom guard (where i remember there was an anti cavalry with range 2) so it should be solved soon.
You might want to make some existing techs a prerequisite, to give opponents time to research the counter techs they would need. Dodge counter takes 18 turns to research, and reach probably won't be the first tech a human player goes for. I'd say make heavy knights a prerequisite, and it should make sense and be balanced pretty well.
We can do it but I don't think it is much needed. Elves start with 50% counter already so they basically avoid 1 in 2 attacks. Upgrades bring it to 80% saving them 4 times over 5