Geo-Force has a connection with the Earth that lets him manipulate it at will. In the game, that mostly manifests itself in being able to create hindering terrain. Though he only does so one square at a time. However, unlike most created terrain like that, it doesn't go away at the end of the turn. They stick around. Though it's not quite permanent. He can have up to four on the board at a time. Geo-Force is also a bit more resilient than a lot of the other figs we've been seeing lately, and also more costly, coming in at 160 points.
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