REDU format ruling
A Hero Emerges
Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)When an opponent's monster declares an attack: Your opponent chooses 1 random card from your hand, then if it is a monster that can be Special Summoned, Special Summon it. Otherwise, send it to the Graveyard.
Rulings
You can only activate this card when your opponent declares an attack. Your opponent selects 1 random card from your hand. If it is a Monster Card, Special Summon it on your side of the field. If not, send it to the GY.
- You can Special Summon a high-level monster, like Dark Magician, with A Hero Emerges. But if your opponent selects a Special Summon-only monster like Dark Necrofear, or a Spirit Monster, it is sent to the GY.
- When Guardian Elma is selected for A Hero Emerges, and you have Butterfly Dagger - Elma on your side of the field, you can Special Summon her, but if you don't have it, then she is sent to the GY.
- You can activate A Hero Emerges even if you have only 1 card in your hand.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.