What problem does it solve? Building a competitive Yu-Gi-Oh deck requires balancing ratios, hand-trap budgets, combo engines, and matchup strategy, and doing this by intuition alone leads to bricking decks and misread metas. This Skill provides structured rules, metrics, and tactics for deck research, building, and optimization. ## Core Features & Use Cases - Deck Construction Rules and Metrics: Enforces main/extra deck size limits, card copy limits via alias and banlist checks, ydkshow ratio thresholds, and a weighted quality score formula for grading builds. - Strategy and Engine Knowledge: Documents combo engines, go-first/go-second plans, Maxx C compromise lines, interruption tactics by engine shape, and advantage/tempo theory. - Playtest and Study Workflows: Evolves deck experience through ygopromcp self-duels and Bilibili master video study, plus PyTorch-based ML utilities for deck modeling. - Use Case: Given a new deck list, validate it with ydkcheck.py, score it against the quality formula, identify its engine shape and choke points, then verify combo lines through self-duels. ## Quick Start Analyze my Yu-Gi-Oh deck list, check its construction against the rules and metrics, and suggest improvements to its ratios and hand-trap lineup.