Difficulty and complexity of 1. deployment: DDD card sets need specific card combinations and complex chain operations when deployed. This means that players need to have a high technical level and strategy to correctly execute the combo of decks. Compared with the first-line card set, DDD card set is more difficult to develop and needs more thinking and planning, so it is classified as the second-line card set.

2. Subtle effect and dependence on specific cards: Although the design goal of DDD deck is to give priority to all calls, its effect may be relatively subtle. This means that the strong performance of the deck often depends on the specific card combination and chain effect. Players need to accurately master the effect and usage of the deck in order to give full play to their advantages in the game. Compared with the first-line card set, the effect of DDD card set is relatively limited, and more skills and experience are needed to play its real potential.