Tengu format ruling
Crystal Beacon
Card effect (current official text)Special Summon 1 "Crystal Beast" monster from your Deck. You must have 2 or more "Crystal Beast" cards in your Spell & Trap Card Zone to activate and to resolve this effect.
Rulings
- You must have at least 2 "Crystal Beast" monsters in your Spell & Trap Card Zone when you activate this card and when it resolves. If the number of "Crystal Beast" monsters in your Spell & Trap Card Zone becomes less than 2 due to an effect chained to this card, then you cannot Special Summon.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.