Holding priority, cast Naru Meha by paying its mana cost.
When Naru Meha enters, it triggers, copying Return to Action, with the copy targeting Naru Meha.
Resolve the copy of Return to Action.
Holding priority, activate Phyrexian Altar by sacrificing Naru Meha.
When Naru Meha dies, it triggers, returning it from your graveyard to the battlefield.
Repeat from step 3.
This clever loop turns Naru Meha, Master Wizard into a self-sustaining engine by utilizing Return to Action to resurrect her every time she hits the graveyard. When Naru Meha enters the battlefield, her ability copies Return to Action targeting herself, establishing a recursive safety net that triggers each time she is sent to the yard. You can then feed that endless cycle into Phyrexian Altar, sacrificing Naru Meha to generate a colored mana of any choice while simultaneously fueling her immediate return to the battlefield.