I don't want to start a flame or to post math here, i think i have some experience and it's something devs can just check better than us and make their decision.
I think the balance between attack units and defend units is not working.
Except big mountains with t2 ranged (and only of some races) there's no way to have an efficent trade defending, with any unit you place, no matter how many you place, your going to loose more than the attacker if the attacker use the right units.
The attack/def values and the terrain bonuses have not been changed since the begin, it's time to think of rebalancing them.
For example make T1 units really better on defence compared with T2,
right now they are a LessExpansive-TimeConsuming-LessPerforming copy of the T2 one, after 2 years almost all medium-big players do not worry of the cost, they worry about the production time and efficency of the troops.
Make any territory defendable by one kind of troop, like plains by spears or t1 cavalry, forest by t1 infantry, ecc... just improve a lot their defence on that kind of terrain.
Improve the malus on the attacking units on terrain they should not fight on.
This kind of things will improve the specialization of player/alliances and will make tactics lot more interesting.
Some other random ideas:
Let us build some kind of temporary wall to help defending camps
or
some structure/spell to temporary change the terrain type for battles.
PS. yes walls help on defence, but in Illyriad you never need to attack a city with a lv20 wall, you can reduce it to 0pop without doing any attack.
Edited by Drejan - 15 Mar 2012 at 23:59