Holding priority, cast Naru Meha by paying its mana cost.
When Naru Meha enters, it triggers, targeting Black Sun's Twilight.
Holding priority, activate Shilgengar by sacrificing Naru Meha.
Resolve the Naru Meha trigger, copying Black Sun's Twilight
Resolve the Black Sun's Twilight copy, returning Naru Meha from your graveyard to the battlefield.
Repeat from step 3.
This clever loop relies on Naru Meha, Master Wizard entering the battlefield to copy Black Sun's Twilight, letting the spell's resolution fish Naru Meha right back out of the graveyard. Meanwhile, Shilgengar, Sire of Famine acts as the essential sacrifice outlet, turning Naru Meha's trip to the graveyard into a Blood token while setting up the loop to repeat indefinitely.