Indestructibility, Blazing Sunsteel, and Guilty Conscience attached to a creature you control.
Steps
Attack with the equipped creature.
When the equipped creature deals damage, Guilty Conscience triggers, dealing an amount of damage to the equipped creature equal to the amount of damage the equipped creature dealt.
Blazing Sunsteel triggers, causing the equipped creature to deal an amount of damage equal to the amount of damage Guilty Conscience dealt to it to any target.