REDU format ruling
Gateway to Dark World

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Target 1 "Dark World" monster in your Graveyard; Special Summon that target. You cannot Summon other monsters the turn you activate this card (but you can Set).
Rulings
- You cannot activate "Gateway to Dark World" if you have already Normal, Flip, or Special Summoned a monster that turn. You can Set a monster (but you cannot Special Summon a monster in face-down Defense Position).
- This card targets 1 "Dark World" monster in your GY.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.