Below is a walkthrough for the Destruction Rains From the Heavens side quest in Tiny Tina’s Wonderworlds. To obtain this quest, speak with Saklas in the Overworld.
Pick up Melee upgrade
Grab the upgrade Saklas.
Reach Desert temple, Abyss temple and Grasslands ruins
Follow the objective marker to each area and complete the encounters there.
Place 3 Cursed Idols
Place the idols where you first met Saklas.
Enter portal
Interact with the red ritual site to enter the portal. Once inside, complete the encounter.
Talk to Saklas
Speak with him to complete the quest.