1.) Place the bone fragments, wood shard, and fertilizer in the bowl on the bottom floor of the zeus tower.
2.) After two rounds, the fertilizer will smoke and can be picked up. Take the fertilizer to the bottom floor of the Danu tower and place between the two trees.
3.) After 2 round, the fertilizer will smoke green. Get kills while with a gun pack with Fire Bomb while standing on the smoke. After a few kills, you will see glowing blue cracks on the ground.