Engineer

Mechanic
The skill Engineer is a skill that revolves around sentries, a Equipment that shoots enemies.

This skill's basic ability makes your sentry twice as stronger, while the aced version lets you toggle your sentry to AP rounds, making it deal 4x more damage but with the drawback of 8x less fire rate.

Strategy
This skill used on its own will make a sentry that can survive for a decent amount of time on lower difficulties but will need to be supported by other sentries skills on higher difficulties. When paired with Sentry Tower Defense and Sentry Mayhem, the multiple sentries can deal good amounts of damage. Note that the 4x damage does not factor in skills, the additional skill damage is added in after the multiplication of base damage.