Kingdom Under Fire: Circle of Doom Cheats

Unlockables
Bless: Complete Normal Mode with Kenal or Regnier
Blizzard: Complete Hard Mode with Kendal
Curian: Complete the game with Celine
Extreme Mode: Complete Hard Mode
Hard Mode: Complete Normal Mode

Character Stats
A character's statistics are always preset to increase with the same application of experience points, thus growing a character into a front-line fighter, ranged attacker, etc.

Curian: HP costs 3, SP costs 24, Luck costs 5.
Celine: HP costs 4, SP costs 20, Luck costs 5.
Kendal: HP costs 2, SP costs 26, Luck costs 5.
Duane: HP costs 3, SP costs 28, Luck costs 3.
Leinhardt: HP costs 3, SP costs 22, Luck costs 6.
Regnier: HP costs 2, SP costs 28, Luck costs 5.

New Life for Low Level Items
High level weapons are great for doing damage until you run out of SP. Rather than throw countless potions at it, synthesize a high level (Attack 100, 1000 or better) to a low level one found in the Forest of Embracing on Normal (the lower the better).

The resulting synthesis will average the SP consumption, and with some luck, allow you to retain a measure of potency of your high level weapon (about 70% of it at worse).

Enemy Cycle
Did you find an enemy you need to harvest a great many of? You can use this exploit on solo (offline) mode. Get to the map the enemy spawns on and kill your fill. Before you load a new map, save and quit the game (anywhere). When you continue on solo mode, your character starts back on that map ... with all the enemies respawned.

Lucky Yellow Potions
You will want to use a yellow potion on high luck characters just before a boss is killed. This greatly affects the quality of the item drops (more so on Hard and Extreme difficulty).

Reducing SP Consumption
If you want to bring down SP consumption rates of your high end equipment, try synthesizing. High end SP recovering rings can be synthesized on your armor and weapons to reduce SP consumption.

Easier Quest Mobs
If you're looking for certain enemies in certain areas, try the following. Every level is separated into regions, and certain mobs only appear in certain zones. Simply find the enemies you need and kill off everything in the area, including the enemies you need to kill. Then, head to the portal leading into the next region, but don't go through it.

Instead, press select, quit your game (making sure to save), and then reboot your saved game thereafter. You'll have full energy, full SP, and be in the same region. What's more, all of the enemies you killed prior to the save/quit will be back. This is especially useful if you find an area that has an enemy or group of enemies that you need to kill mass quantities of.