With Pure Reflection in play, any time a player plays a creature spell (note that the spell need not resolve; even if countered, you still get the effect) a triggered ability goes on the stack.
This triggered ability has this instruction:
"Destroy all Reflections. Put a white Reflection creature token into play with power and toughnes of X, where X is the creature spell's converted mana cost."
Note that this is not a "clone" of the creature. It simply has power/toughness equal to the CMC of the spell that triggered it. Note also that the token creature will come into play before the creature that triggered the ability. Finally, note that the creature spell must be played and not simply "put into play."
The most interesting use of this card, in my opinion, is the Pure Reflection/Unnatural Selection combo, which allows you to change your opponent's creatures into Reflections any time someone plays a spell in order to wipe them out.
I don't see any useful interaction with Dual Nature, since the Reflection token won't trigger Dual Nature, and the Dual Nature token won't trigger Pure Reflection. The other things Hetemti mentioned work alright, though not to the great advantage that Unnatural Selection affords.