Edison format ruling
Time Wizard

Card effect (current official text)Once per turn: You can toss a coin and call it. If you call it right, destroy all monsters your opponent controls. If you call it wrong, destroy as many monsters you control as possible, and if you do, take damage equal to half the total ATK those destroyed monsters had while face-up on the field.
Rulings
- The effect of Time Wizard is a Ignition Effect, and therefore can only be activated during your Main Phase 1 or 2.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.