If Morselhoarder has any -1/-1 counters on it, activate it by removing a -1/-1 counter from it, adding one mana of any color.
Repeat step 1 as necessary until Morselhoarder has no -1/-1 counters on it.
Activate Goblin Bombardment by sacrificing Morselhoarder.
When Morselhoarder dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Resolve the Goblin Bombardment ability.
Repeat.
This elegant loop turns Morselhoarder into a self-sustaining engine of destruction, fueled entirely by the passive power of Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight. While Isilu grants your nontoken creatures persist, Morselhoarder's natural -1/-1 counters can be stripped away using its own mana-producing activation. Once those counters are gone, you sacrifice Morselhoarder to Goblin Bombardment to deal damage, triggering its persist to bring it right back to the battlefield with a fresh -1/-1 counter ready to be converted into mana once more.