TDS - Tower Destiny Survive

A zombie apocalypse-themed tower defense survival game where you collect building blocks during exploration to gradually expand a mobile fortress, and equip towers with firearms and defensive weapons. To withstand waves of zombie attacks, you'll need to consider weapon placement and fortress upgrades in addition to direct shooting, in order to maintain your defenses and advance. It combines shooting, construction, and strategic development.

That item is really needed for leveling up in the late game.