These TCG rulings were issued by Upper Deck Entertainment and have since been deemed unofficial by Konami. They were previously considered official and can still be correct, as long as they follow the official gameplay rules, or unless Konami has issued a ruling that says otherwise. References: 
You can put 2 or more counters on a Spell Card if you activate 2 or more "Magic Reflectors". When the Spell Card is destroyed, remove the counters on it 1-by-1.
You can activate "Magic Reflector" and put a counter on a Monster Card equipped to "Relinquished", and if the equipped card would be destroyed, remove 1 counter instead.
If "Imperial Order" is active, and if a Spell Card with a counter on it would be destroyed, the counter is removed instead. "Imperial Order" does not negate the function of counters created by the effect of "Magic Reflector".
If a Spell Card with a maintenance cost has a counter on it, such as "Messenger of Peace", and you choose not to pay the cost, the Spell Card is still destroyed.
If "Swords of Revealing Light" has a counter on it, it is still destroyed at the end of the opponent’s third turn after it was activated.
Emergency Provisions: The effect of this card does not "destroy" your Spell and Trap Cards; it "sends them to the Graveyard." So, for example, you may send a Spell Card to the Graveyard with a counter on it from "Magic Reflector". You can also send "Fusion Sword Murasame Blade" even though it cannot be "destroyed".
Nightmare's Steelcage: If you use "Magic Reflector" to put a counter on "Nightmare's Steelcage", it is still destroyed during the opponent's 2nd End Phase after it was activated. You cannot remove the counter instead.
Union Monster: ... You can use "Magic Reflector" to place a counter on an equipped Union Monster and, if the equipped monster would be destroyed in battle, you can remove the counter instead so neither the equipped monster nor the Union Monster are destroyed.
Out of Date
If a Field Spell Card has a counter on it and a player activates a new Field Spell Card, the Field Spell Card with the counter is still destroyed.[Out of Date 1]
Out of Date
↑According to the new game mechanics for Field Spell Cards, now both players can have an active Field Spell Card on their field at the same time; also, if a player plays a new Field Spell Card while they already control a Field Spell Card, the previous Field Spell Card is simply sent to the Graveyard not destroyed.