Art the Clown is back! Or, is... in his first outing! Depends on where you put the previous Damien Leone shorts in the hierarchy, but Terrifier is a full 90 minute romp where Art the Clown does (blog post) what Art the Clown does best. No, horror movies that is (blog post) not explain his motives in the slightest.
Source: Terrifier Movie Review - Decker Shado