Let me see if I understand this correctly, you want a door that rises up out of the ground. Is the door in a wall? Or is it just standing there by itself and you could walk completely around it? Do you want the door to look like a typical hinged door? or is it supposed to look like a sci fi hatch?
Then the door will open in some kind of sci fi way, revealing an alternate dimension on the other side.
I’m not quite sure what you mean about the scope sucking in pieces of the room and blowing it into the ground making it tiles. Do you mean tiles like a checkerboard? or is the pathway on the other side of the door an empty void and the furniture is used to make a floating bridge to the other dimension? Or does the room that the door sits in get broken up into tiles that you have to navigate to reach the door?
I guess I would probably build something like this with script movers for each part of the door. Move all of them up from the ground at the same time, and then rotate or shift each piece individually to reveal the dimensional door.
For the Dimension door, I would use a camera that would create a “mirror” surface that will show you the world on the other side of the door. Maybe combine that with another brush that has some glow effects on it. I’ve never made a mirror surface before but I know there are tutorials on it. I would just use setstate commands to turn the door visible after the script mover doors have risen from the ground, but before they open up.
If you want this door to float in the center of the room so that people could walk around it, I would use a teleporter so that anyone trying to “enter” the mirror would simply teleport to the other side with some flashy special effects similar to what firefly is doing with his Castle Eltz map.
Any props that you want to move would probably have to be script movers as well. Put them on a path and move them to the door. If the path ends at the door, they will disappear when they reach the last point. Then use a setstate function to turn on static pieces on the other side. If you want the room itself to break up into tiles, make func_static groups out of the parts you want to hide and setstate them invisible. You can also use flashy effects here as well. Or maybe you want these tile pieces to break up? You could use a func_explosive on each group and trigger those instead so it looks like the room is breaking apart.
Underneath any floor, cieling, or wall sections that I wanted to disappear, I would put a skybox texture with a starfield on it to create the illusion that the remaining parts of the room are floating through space with the dimensional doorway at the other end leading to the princess.