Activate Goblin Bombardment by sacrificing Archon of Falling Stars.
When Archon of Falling Stars dies, it triggers, returning Necromancy from your graveyard to the battlefield.
When Necromancy enters the battlefield, it triggers, returning Archon of Falling Stars from your graveyard to the battlefield, and attaching Necromancy to it.
Resolve the Goblin Bombardment ability, dealing 1 damage to any target.
Repeat.
This elegant loop relies on a closed-circuit recursion between the graveyard and the battlefield, fueled entirely by the sacrifice outlet provided by Goblin Bombardment. By sacrificing Archon of Falling Stars to the Bombardment, you trigger its death ability to pull Necromancy right back out of your graveyard. As Necromancy enters the battlefield, its own trigger targets and resurrects Archon of Falling Stars, attaching itself back to the Archon in the process. Because Goblin Bombardment lets you repeat this exchange indefinitely for just a creature, you can cycle the pair back and forth as many times as you need to blast away your opponents with infinite damage.