The Idealist
(the following is written by the Site Administrator based on the deckbuilding of various duelists - possibly unfinished)

The particular structure of Duel Masters' rules allows the game to appeal strongly to idealistic playstyles. Since any card may be used as a mana card, and all cards are worth the same one mana count at any given time, the progression through turns is well structured. In other games, any amount of randomness causes relatively high fluctuations in performance. Not so in Duel Masters.

With the ability to play four copies of absolutely any card (KC format) or at least four copies of nearly every card (JP format) it lowers the chances of not getting needed cards. The mana system, in turn, solves the issue of what to do when one gets too many of a card. Even with three copies of a single card being unluckily drawn in a player's starting hand, this may often pose no reason for serious concern. The 'unnecessary' copies can be placed into the mana zone, and other cards put to use as they are drawn.

This gives players the ability to design decks based on certain ideal sequences of play, and choose card ratios that reflect these ideal situations. By placing more than one card of similar effect and cost into the deck, one can strongly increase the likelihood of these ideal situations. Let us take, as a simple example, a deck which wishes to consistently cast the Water Spell Crystal Memory on the third turn of play.

In order to achieve this goal, the deck must ensure that somehow it has sufficient mana to fulfill the cost requirement of Crystal Memory on its third turn, and that the card is available for casting. For this reason, the player can justify putting four copies of the card into the deck. If they draw too many of them in the first few cards, at least one of them can be used as a mana resource, and this facilitates casting one of the others. The second issue is to ensure that the mana is ready one turn 'early'.

There are multiple ways to achieve this, but the example was chosen specifically for simplicity. There is only one turn in which this aim can be achieved. The second one. A card mut be played on the second turn that prepares for the use of the spell on the third. The important thing to note here, is that the specific card is not relevant to the example, and may not even be particularly relevant to the duelist. What matters is their ability to place, into the deck, a large number of cards that attain the objective, without initially worrying about 'drawing too many'.

Their ideal situation then becomes that of using a facilitating card on their second turn and casting Crystal Memory on the third. They could play eight, ten, or even more than a dozen cards, total, that would make it possible to cast the spell. If they draw 'too many', just use some as mana cards. In the same manner, they could play four of the card that they intend to actually search for with their Crystal Memory. Drawing that card certainly would not usually be counted as a problem.

The development of an ideal strategic sequence is rather easy, and the structure of the game makes the execution of the ideal a likely enough occurrence that the deck can be considered stable in attempts to do it.