Military action
Elves are beaten back into their forest, which they prepare to pull into the Feywild again. They unleash a magical plague into the goblin legions.
Four elf legions are annihilated in human lands. Two goblin legions break into the weakened Doroinir Nimloth and wipe out eight entire armies of elvenkind by adapting their tactics faster than the elves could. The elves buy themselves time to shift Doroinir Nimloth again into the Feywild by unleashing a magical plague. It worked better than expected, and the goblins flee elf territory as the elves shifted away.