You can only activate “Chaos Sorcerer”’s effect during Main Phase 1 or 2 of your turn.
You can only activate “Chaos Sorcerer”’s effect once in a turn.
If “Chaos Sorcerer” attacks, you cannot use its effect during Main Phase 2. But if “Chaos Sorcerer” did not attack, you can activate its effect in Main Phase 2.
If you select a face-up monster with “Chaos Sorcerer”’s effect, and your opponent chains “Book of Moon” to flip the monster face-down, then “Chaos Sorcerer”’s effect disappears. But even if “Chaos Sorcerer”’s effect disappears, its effect was activated so it cannot attack or activate its effect again.
If “Chaos Sorcerer” attacks and the attack is negated with “Magic Cylinder”, “Chaos Sorcerer” cannot activate its effect in Main Phase 2.
If “Chaos Sorcerer” attacks and a replay occurs, and you decide not to attack again with “Chaos Sorcerer”, you cannot activate “Chaos Sorcerer”’s effect in Main Phase 2.