REDU format ruling
Mega Ton Magical Cannon

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Remove 10 Spell Counters on your side of the field. Destroy all cards on your opponent's side of the field.
Rulings
- Removing Spell Counters is a cost. If you do not have 10 Spell Counters you cannot activate Mega-Ton Magical Cannon.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.