> I'd like to place numerous vias in a cluster to assist with heat > transfer or RF shielding integrity. How can I do this in PCB?
If what you mean is "I'd like a bunch of vias with solid connections to the plane, without thermals or clearance" then the only way to do so is to add a second polygon in that area that does not have the "clear pins/vias" flag set. Amusingly, the way to do this is to use the "change size" hotkeys (S or Shift-S) on the new polygon. There is currently no way to specify this on a per-via basis.
