You cannot activate “Physical Double” during the Damage Step.
If you activate “Physical Double” and your opponent chains “Ring of Destruction” to destroy his targeted monster, the effect of “Physical Double” disappears.
You can target a Monster Token with “Physical Double” to create a Mirage Token copy of it.
When the targeted monster’s Level, Attribute, etc. are changed after “Physical Double” resolves, the stats of the Mirage Token are not changed. When the targeted monster’s Level, Attribute, etc., are changed before “Physical Double” resolves, the changed stats are adopted by the Mirage Token.
If a Field Spell Card was active before resolution of “Physical Double” that applied to the targeted monster, it applies to the original monster and to the Mirage Token. So if a Field Spell Card was increasing ATK by +500, the original would get +500 ATK and the Mirage Token would get an additional +500 ATK, for a +1000 ATK bonus total for the Mirage Token over the printed ATK of the original monster. Likewise, when “A Legendary Ocean” is active, and you activate “Physical Double” targeting a WATER monster, the Mirage Token’s Level Stars are 2 fewer than the printed Level Stars of the original targeted monster.