Activate Shilgengar by sacrificing Melira's Keepers
When Melira's Keepers dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to its static effect.
Resolve the Shilgengar ability.
Repeat.
This elegant loop relies on Isilu, Carrier of Twilight's static ability to grant your other nontoken creatures persist, creating a steady stream of dying fodder for Shilgengar, Sire of Famine to sacrifice into Blood tokens. Because Melira's Keepers features a static ability preventing counters from being placed on it, it continuously cheats death by returning via persist completely unburdened by -1/-1 counters. Eirdu, Carrier of Dawn sets the stage for casting your creatures with convoke before you ever need to flip into its twilight counterpart.