Step 1:

Set up your stats using the Character Management link from the events channel.
You must do this or the battle system will not work for you.
The stats edit panel will not appear in the other channels.
The help file there will explain the meaning of the stats.

Step 2:

Choose a battle mode using /fightmode [open|strict]
It is also recommended to turn on tracking mode using /track. This will allow you to watch the contents of the fight queue to ensure the correct fighter sells the correct attack.

Step 3a:

In strict mode you are not allowed to enter values greater than the maximums you've chosen.
Use the /medi command to set your HP/SP/MP to their maximum to begin the match.

Step 3b:

In open mode you are allowed to enter any values.
Use the /set command to set your HP/SP/MP to the desired values.
/medi will still set your stats to their strict mode maximums.

Step 3c:

Determine who starts, /roll is recommended. (/roll with no arguments defaults to 1d20)

Step 4a:

On your turn, do one of the following: /fight, /special, /defend, /rest.
/fight will execute a normal attack.
/special will execute a powerful attack, expending a little extra energy to provide a bonus to your attack power.
/defend will grant you a bonus to your defense power on the next hit you take. It will only announce that you have passed on your turn.
/rest will regenerate some of your energy the next time you attack or are attacked. It will only announce that you have passed on your turn.
In open mode, /rest will regenerate both SP and MP, even if your character was /set initially with either at 0. This is normal and cannot be changed without compromising the flexibility of the system.

Step 4b:

In open mode only, boss characters wishing to execute a multi-target attack should use /bossfight or /bossspecial.
Executing a multi-target attack will not use any stamina or mana until the attack is sold. Make sure your character has a sufficient amount of power beforehand.
If the character runs out of power, additional targets will not take damage.

Step 5:

The target must use /sell to determine the outcome of the strike if /fight or /special was used. They should then use /me to describe the action. (If desired)
If the previous turn was passed, no /sell should be executed. Instead, the turn passes on, with the next combatant at Step 4.
If a boss attack (special or normal) was executed, all targets need to /bosssell the attack. The boss's stats will be adjusted after each one.

Step 6:

If both players pass in turn (or all players in a multi-way battle), then next player MUST execute an attack.
If that player used /rest, their energy will still be restored.
If that played used /defend, they will instead be granted a bonus on their attack rather than their defense.

Step 7:

Continue from Step 4 until one player remains.