Cards
There are over 800 different cards in the game, consisting of two different types: Monster cards, which take part in the actual fight, and Spell cards, which cast effects on various elements of the game, such as monsters and the terrain on which you fight. When building a deck of 40 cards, you can choose one of your Monster cards to be a Deck Leader and, therefore, cast Spells and conjure other Monsters. Select a Monster card in the deck-building screen and press "Start" to make that card the Deck Leader. Additionally, if you don't like a card, you can use the Reincarnation option to spawn three new cards from the discarded one.
Terrains
Terrains are the individual squares of the playing field where players battle with their cards. Take care as to what terrain your Monster will step on because it affects your Monster. Terrains can have desirable and undesirable effects on different types of monster cards. For example; Sea terrains benefit any Aqua, Fish, Sea Serpent and Thunder cards, but it can harm Machine and Pyro cards. However, there are many Spell cards that can change the terrain.
Making Cards More Powerful
To make your Monsters more powerful, consider combining cards. If you combine two Monsters in an act called Fusion, you can create a new monster of increased power. Additionally, if you use a compatible non-Monster card, you can perform what's called a Power-Up, which increases your Monster's power. Take care to note what cards are compatible with your Monsters by looking at the Detailed Information Contents view screen in the game. Select "Power-up Card" or "Special Info" to see what's compatible. If the card you want to combine with your Monster is incompatible, it could result in cards getting discarded, which may be undesirable if you're using rare cards.
Choosing Sides
When you begin "Yu-Gi-Oh! The Duelists of the Roses," the game requires you to choose a group to side with for the rest of the game: either the Red Rose or the White Rose. Choosing a different side means fighting different enemies. However, in both paths, the final boss is Manawyddan Fab Llyr. In the Red Rose version, he is a Skull Knight, while in the White Rose version, he's a Chakra, and is more powerful than in the Red Rose version.