The Shakri

In Season 7 Episode 4, The Power of Three, The Doctor, Amy, Rory and Brian Williams (Rory's dad) begin the year and the slow invasion.

Amy and Rory wake up to find cubes, everywhere. Brian cam over to help figure out what the cubes were. They were solid black, and they did nothing. They were just cubes. The Doctor shows up as well. Little did the Doctor know, it was going to be a while before they found out what was going on.

The Cube

After a year, the cubes began "waking up" they all did something different, controlled emotion, played music and even shot at people. 

The cubes eventually shot out an electric pulse, stopping the hearts f many humans near by, and that is when things start to get interesting. The Doctor finds one of seven portals to a space ship.  The space ship belongs to the Shakri, who the Doctor believed were just a myth to keep the children of Gallifrey in their their place. He is soon greeted by a hologram of a weird looking black-cloaked humanoid. 

The apparition warns that the Shakri plan to release a second wave of cubes and cause further deaths, to stop the human race from colonizing space. 

The Apparition

The Doctor takes care of things, like usual and the world goes back to normal. I have included one of my favorite scenes and a trailer below.