Cast Traveling Plague by paying 3, attaching it to another creature you control.
When Traveling Plague enters, Ajani's Chosen triggers, creating a creature token.
Activate Goblin Bombardment by sacrificing the creature Traveling Plague is attached to.
When the creature dies, Traveling Plague triggers, returning itself from your graveyard to the battlefield attached to the token created in step 2.
When Traveling Plague enters, Ajani's Chosen triggers, creating a creature token.
Resolve the Goblin Bombardment ability.
Repeat from step 3.
This clever loop transforms a creeping curse into a devastating engine by turning Traveling Plague’s persistent nature against itself. As the Plague sits on a creature, Ajani's Chosen stands ready to reward every single entry of the Aura with a fresh 2/2 Cat token, while Goblin Bombardment provides the sacrifice outlet needed to repeatedly send the enchanted creature to the graveyard. Because Traveling Plague automatically returns itself to the battlefield attached to your newly created Cat whenever its host leaves play, you can repeat this cycle endlessly to machine-gun down any target with infinite damage.