Empowered Autogenerator and Hateflayer in exile (Empowered Autogenerator and Hateflayer exiled by Myr Welder).
Myr Welder and Encroaching Mycosynth on the battlefield.
Myr Welder does not have summoning sickness.
({3} magic symbol) available.
Steps
Activate Myr Welder using Empowered Autogenerator's ability by tapping it, putting a charge counter on Myr Welder and adding ({R} magic symbol) for each charge counter on Myr Welder.
Activate Myr Welder using Hateflayer's ability by paying ({2} magic symbol) ({R} magic symbol) and untapping it, dealing damage equal to Myr Welder's power to any target.