“Damage” is the base state for calculating tower projectiles and other abilities such as Ultimate Weapons. “Damage” can refer to a multitude of different aspects of the game, including, but not limited to:

Lab

The Damage Lab is unlocked when you unlock labs in Milestones at Tier 1 wave 30. It increases the increments for each damage workshop level and its maximum value.

Workshop & Workshop Enhancement

Card

Perk