Do the locations need to be in the same region?
No. Teleport effects ignore regional boundaries unless otherwise specified, and the only restriction on this effect is that the locations be a chess knight's move apart on the board. For example, if A is a void square, and B contains a site, Flanking Maneuver can move units from that void location to either the surface or subsurface of the site.
Market
$0.20
Low
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$0.23