Rulings
Era-accurate rulings per format — how cards actually worked in April 2005, March 2010, and September 2012, not how they work today. Every entry keeps its source.
Goat
April 2005 · UDE-era rulings
822 cards covered
Edison
March 2010 · rulings + era card text
2111 cards covered
Tengu
Sept 2011 · native Tengu-era rulings
2115 cards covered
REDU
Sept 2012 · nearest-era rulings (Tengu)
2139 cards covered
Advanced
Current · via Konami's official database
Rulings data courtesy of Format Library — formatlibrary.com (open data on GitHub). Go read their format guides; they’re the gold standard.