REDU format ruling
Judgment of Thunder

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Activate only when you Summon a Thunder-Type monster(s). Destroy 1 card your opponent controls.
Rulings
- Judgment of Thunder cannot be activated in the Damage Step.
- Judgment of Thunder targets 1 card your opponent controls.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.