Arena is where you can fight with your units to gain exp and gold. It is a great way to level up your army and win alot of cash. But if you are not careful, you might lose your unit for the rest of the game play.

Where are the Arenas?
There are only 4 chapters with arenas, 16X, 20, 23, and 29X, and chapter 29X only allows you to use the arena for 5 turns, so only the first 3 chapter's arenas are really usable.

What are the rules?
When you step in the arena, a person will welcome you and ask you to wager certain amount of gold. You can either accept or deny. If you accept, you'll be battling with a random enemy unit. The two units take turns attack each other in a death fight. If you win, you'll win double the money you wagered, if you lose, you lose your wager and your unit dies which means you have lose that unit for the rest of the game play. You can also quit during the battle after you have accepted to wager. Press "B" during the firght will end the battle and you'll lose any gold that you have wagered. If you denied to wager any gold, nothing will happen and the unit is still free to move around.

Things to know about the arena
1. The weapon you use in the arena are all provided by the arena, meaning you have to fight with iron weapons in the arena. The good side is that you don't need to spend gold and buy weapons because the usage of your own weapons don't drop. The bad side is the enemies that you are fighting usually have better weapons.
2. The two units attack each other by rounds. For example, you'll go first, then the enemy attacks. If your unit's speed is greater then the enemy's speed by 4 points, you'll attack again, and ending one round. If your speed is less than the enemy's by 4 points, the enemy will attack again and ending one round. If your speed and the enemy's speed are more or less the same, then this round will end after each have attacked once.
To sum up:
If speeds have a difference of 4
Round 1: You -> Enemy ->you again/enemy again -> on to round 2
Round 2: You -> Enemy ->you again/enemy again -> on to round 3
If speeds DON'T have a difference of 4
Round 1: You -> Enemy -> on to round 2
Round 2: You -> Enemy -> on to round 3
3. Pressing B doesn't always get you out of the arena. It will only allow you to end the battle right before the next round.

Amount you can wager and how it'll affect the enemy you are about to face
Basicly, it's like this:
below 600 gold ---- very easy
600-699 gold ------ easy
700-799 gold ------ medium
800-899 gold ------ hard
900 gold and up --- very hard
I personally only wager 699 and below just to be save.

Tips and Tricks:
Will, now that you all know the basics of the arena, lets get on with the tips and strategies for winning.
First off, to be very sure of always winning, never accept wager greater than 700. If the wager is larger than 700, decline it and reenter the arena again so wager amount will change into a different one. Once you found an acceptable wager, say yes and begin the battle.

See the picture above?
HIT means the chance of hitting the opponent.
DMG means the damage the opponent will take after been hit.
CRT means the chance of performing a critical hit.
When you first enter the battle, quickly look through these numbers, if the enemy has a CRT number greater than 1, it's better to end the battle by pressing B just to be save. But if you want to take chances and continue, don't cry about having to restart the chapter because you lose your unit due to a critical hit.
Next, take a look at the HIT number, always treat the enemy's HIT number as if it's 100 unless it's about 0-50. If yours is about 70-100, then you are probably fine, if not, press the B button if you don't want to take a chance.
Finally, try to calculate how much hp you'll have left after the enemy attacks by subtracting your current hp by the DMG number, same goes to finding out how much hp the enemy will have after your attack. If you think you stand a chance of winning after 1 or 2 rounds, sit back and watch the victory. If not, start smashing the B button.
That's every thing. :)