Often seen in the middle of the night, I can also send an ball into flight. What am I?

In game room, puzzles abound, Pieces scattered, not yet crowned. With care and love, they unite, Creating harmony, oh so right. In other words... Avengers ___

One thing goes wrong, then another joins in, before you know it, the madness begins.

On two sides it's merging, the Pacific and the Atlantic. East is flat with sandy beaches, the people are frantic. The other side is rough, making tech that's really big. If you hear that this is clear, you know you won't get hit.

Intense interrogation, bars in parallel, Or ostentatious dentistry that shows you're doing well