RadiusImpulse. I did this too, and I bet you were on that futuristic escape-ish server when you saw this. So, I did, on the room's baseplate:
Onplayertouch-named Brick [power core]-firerelay
then on an invisible-nocolliding brick in the middle of the core:
Onrelay-self-radiusimpulse [24] (<-- because I was using a 48x baseplate, and the core was in the center) [-200] (<--- This will make a pull over the 24-block range with a power of 200) [15] (<--- Upward pull, helped because it wouldnt lift a person at first, Im still not sure about what it does exactly.)
Hope this helped!