Edison Format · March 2010
"Turbo Booster" can only be Special Summoned by its effect during your own Main Phases.
The second effect of "Turbo Booster" is an Ignition Effect that you can activate during your Main Phase 2. Tributing "Turbo Booster" is a cost. This effect targets your opponent's monster.
If you Special Summon "Turbo Booster" during your Main Phase 2 you can still activate its second effect.