Resolve Preston's trigger, creating a 3/3 token copy of Ruthless Technomancer.
The token enters the battlefield, causing you to sacrifice the nontoken Ruthless Technomancer and create three Treasure tokens.
In response to the remaining ability, activate the token Ruthless Technomancer, paying ({2} magic symbol) ({B} magic symbol) and sacrificing two Treasure tokens to return Ruthless Technomancer from your graveyard to the battlefield.
Ruthless Technomancer and Preston trigger.
Resolve Ruthless Technomancer's trigger, sacrificing the token Ruthless Technomancer and creating three Treasure tokens.
Resolve Preston's trigger, creating another 3/3 token copy of Ruthless Technomancer.
The token enters the battlefield, causing you to sacrifice the nontoken Ruthless Technomancer and create three additional Treasure tokens.
Repeat from step 4.
Once you have infinite Treasure tokens, you may activate Ruthless Technomancer any number of times, sacrifice the creatures you return any number of times with Ruthless Technomancer, and trigger Preston any number of times.
Results
Infinite blinking of creatures and creature cards in your graveyard.
Infinite colored mana.
Infinite creature tokens.
Infinite death triggers.
Infinite ETB.
Infinite LTB.
Infinite sacrifice triggers.
Infinite Treasure tokens.
Return all creature cards from your graveyard to the battlefield.