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Added to most home versions, The Duel is a useful training ground for familiarising yourself with the various enemies and bosses in the game, as well as being a good challenge in its own right.

With two players it's a versus mode: you can use all the various attacks to fight each other. Note that Gilius Thunderhead deals double damage in versus mode.

The single player is more interesting. You start with eight life bars, and you cannot heal or use any magic. Just as in the normal game, weak attacks can damage a life bar without actually removing it. Below your life bars are the enemies' life bars, useful for telling how close they are to death. When multiple enemies are onscreen the life bars are somewhat shared. It is sometimes possible to focus on one enemy and then hit the other only a few times to take them down quickly.

In the Genesis version, if you complete all the challenges you will be told "Congratulations! You’ve won against all of your enemies. You can get more power and techniques because of your victory in this duel!! Now, let's try Arcade mode." Despite this description, no new moves or health/magic boosts seem to have been unlocked by beating The Duel.

In the Genesis version, there are twelve rounds:

1. a Silver Longmoan on a Chicken Leg
2. two Silver Heningers
3. a Silver Heninger on a Red Dragon
4. two Skeletons
5. two Red Longmoans
6. two Lemanayas on Red Dragons
7. two Dark Heningers and a Dark Longmoan
8. two Purple Skeletons (exclusive to The Duel)
9. two Bad Brothers
10. Lt. Bitter
11. two Gen. Heartlands
12. two Gen. Bitters

If you win you see the same credits roll as in the other modes. If you lose, you see a standard Game Over screen, followed by the message "Unfortunately, you are defeated on the way to glory. Let's try another Duel." Regardless of whether you won or not, you'll get to see your Score along with what round you got to.

In the MS-DOS version, there are fifteen rounds:

1. a Green Heninger
2. a Gold Longmoan
3. a Red Heninger and a Red Longmoan
4. a Storchinaya
5. a Red Heninger, a Lemonaya, and a Red Longmoan
6. a Green Longmoan on foot and a Green Heninger on a Chicken Leg
7. a Gold Longmoan on foot and a Gold Heninger on a Red Dragon
8. a Red Longmoan, Gen. Heartland, and a Red Heninger
9. two Skeletons
10. two Lemonayas on Blue Dragons
11. two Lt. Bitters and a Silver Longmoan
12. two Gen. Bitters
13. Col. Bitter, a Red Longmoan, a Red Heninger, and Gen. Heartland
14. two Skeletons and Death Adder
15. two Skeletons and Death Bringer

NOTE: The Life Bars are invisible starting with Round 9.

There is no congratulatory message or credit roll in the MS-DOS version; you will go directly to your score after the last round if you win.