Empowered Autogenerator and Knacksaw Clique in exile (Empowered Autogenerator and Knacksaw Clique exiled by Myr Welder).
Myr Welder and Encroaching Mycosynth on the battlefield.
Myr Welder does not have summoning sickness.
({1} magic symbol) available.
Steps
Activate Myr Welder using Empowered Autogenerator's ability by tapping it, putting a charge counter on Myr Welder and adding ({U} magic symbol) for each charge counter on Myr Welder.
Activate Myr Welder using Knacksaw Clique's ability by paying ({1} magic symbol) ({U} magic symbol) and untapping it, causing target opponent to exile the top card of their library, and allowing you to play that card this turn.