The discussion here goes where I thought it would go.
Lets compare Reverse Time and Time Paradox:
Both Reverse time and Time Paradox
send a card to your opponent topdeck position.Reverse Time is a
creature control card (it sends the target creature back into it's owner deck), not destructive but still controlling. In combination with nightmare, silence or quanta denial, you can forbid the creature to come back.
Time Paradox is not, the target creature stays were it is. A copy is sent on the top of the deck. With Reverse time you can do perform some
quanta denial. This is particularly efficient against deck using quanta generating spells (Nova, immolation).
No way to do that with Time Paradox.With Reverse time you can rewind your own creatures in your own deck
preventing you to deck out or healing them from poison, BB or freeze.
Time Paradox sends all cards to the top of your opponent deck. So, you cannot do the same thing.With Time Paradox you can choose the creatures you send to your opponent's top deck also among your own. You will likely take a creature that your opponent cannot play, in order to forbid him a draw. Combined with nightmare you can prevent two draws.
Draw denial is not achievable with Reverse Time alone. Combined with nightmare you just improve the CC effect.Combined with Mind-gate, Time Paradox allows you to
copy your own creatures. In the same case, Reverse Time makes you fill your hand with your opponents cards.Combined with GotP, Time Paradox can
force your opponent either to discard his own card or to loose HP. No way to do that with Reverse Time alone (you'll need nightmare at least).[/list]
To summarise, RT is a CC and a quanta denial card whereas Time Paradox is a draw denial card. It is a less efficient draw/play denial card than nightmare but it has other synergies (among which mind-gate and GotP).
In order to give you a bit more hints as why I did this card. I think that this other card of mine "Sand Ant (
http://elementscommunity.org/forum/index.php/topic,23362.0.html)" was a good idea but it seems to be able to perform a draw lock (with mindgate/mitosis and fractal) that I didn't foresee. This card being a spell and not a creature avoids this trap.