Defensive Strat.

Long before the tourney started, I'd tested out how experience was split, and it came out that the commanders in the same army equally split the experience no matter how much they contributed to the kills. So if you had two commanders in one army, and one had 1 knight under him and the other had 100 knights under him, the experience gained was still equally split.

On the very first day of the tourney, I had stacked two armies: one with a few knights under him to activate the stone and 1 with my full army under him. Never having used messengers before, I had assumed I could specify that only the "place holder" army would be recalled. I ended up leaving him on the stones rather than lose out on the night for the other army, and it looked like the experience was equally split between the two commanders.

More recent tests, however, do make it appear that this has changed. For stacked armies, I suspect it does have to do with the % of the total attack or defense power contributed by the army, but I'm still testing this.

I don't suppose a knowledgeable GM would care to confirm how experience is split?

I see the tourney as a contest of economics - the player that can keep making defensive armies to feed into the battle will have the most XP gain.  Of course, if a player started the tourney with a large defensive army, that player would have a starting edge.

Also, Cmdr upgrades are important.  Most of us probably didn't have any Force of Will since it has not offered any advantage to defensive cmdrs.  Now, at least 2 levels are very helpful in fending off the nasty spell casting monsters.

Another question for you: What happens if a commander's life reaches 0 while occupying a square, but some of his army remains? 

The players split the exp based on how much each player's armies contributed to the fight, then that player's commanders split the exp equally among all commanders.

For example, if Player A has 10k troops on a square and Player B has 500 troops on a square.  The player armies are such that Player A's commander Alfred has 500 troops and Player A's commander Anathema has 9500 troops.  Player B's commander Bert has 499 troops and Player B's commander Bartholomew has 1 troop.  For the sake of simplicity, all troops inflict the exact same number of casualties (although this is unlikely given commander skill bonuses and what-not, I'm just saying that to simplify the math).

So the players are attacked by 10,500 exp worth of ghosties (also not likely, but makes the math easier).

The experience would be allocated as follows:

Player A: 10k total experience

Alfred: 5k exp

Anathema: 5k exp

Player B: 500 total exp

Bert: 250 exp

Bartholomew: 250 exp

Obviously there are applications for players who have multiple cities who have the armies wiped out of a city with a commander they are using for the challenge.  The player can then send the commander with a force of 1 and an army from another city to continue to gain experience, although this would only be half as effective as sending him alone with troops from his own city.

Alliance mates could also support each other in this way.

I consider this to be a game mechanic rather than an exploit, but if others feel differently, feel free to comment.

So it would be a better strategy for smaller players who are still "in the hunt" to share a square with another player from a different league (or even the same league if you just want to be a good alliance mate) in order to give commanders a better chance of survival and perhaps increasing overall exp for both or all players involved.

Whether this is effective will depend on how big the armies get -- if they get to the point where they can wipe out smaller players in one go, they might do well to band together.