Deck Leader is a position a Monster Card can hold in Yu-Gi-Oh! The Duelists of the Roses. The Deck Leader serves as the player's mobile base, representing their Life Points, Summoning monsters from the hand, and Setting Magic and Trap Cards from the hand.
When the player receives their starter Deck from Simon McMooran at the beginning of the game, their Deck Leader is already set.
As the player Duels, cards they use (Summon, attack, defend, inflict critical hits, etc.) frequently earn XP. XP is not visible to the player. After a monster has gained enough XP, at the end of a Duel the monster will be promoted. All monsters in the player's Deck can be promoted, not only their current Deck Leader.
Losing duels can get your Deck Leader demoted. Losing enough Duels will cause monsters to go down 1 Rank.
All Monster Cards start with no Rank (Non Commissioned Officer). After their first promotion, they are ranked Second Lieutenant (2LT in the game's shorthand). The full list of ranks are detailed below.
Deck Leaders have special effects called Leader Abilities. The player's first Deck Leader starts with a Leader Ability. Other Monsters Cards that become promoted can earn Leader Abilities, although the game does not explain when or how this occurs.
Various Leader Abilities include: