The Hoth: Main Power Generators site produces an energy shield which is "strong enough to withstand any bombardment." This shield protects much of Hoth for the Light Side by preventing many forms of Dark Side deployment and movement; however, the Dark Side may deploy or land beyond the shield and "march in" to Echo Base.

The energy shield will extend at least as far as the 3rd marker, so an exterior site with a marker number of 4 or more is needed to establish the shield's boundary. Therefore, whenever you are about to deploy the Main Power Generators (even as your starting location), you must check to see if marker 4, 5, 6, or 7 is on table. If not, you must immediately deploy your 4th marker site -- the North Ridge -- from hand or Reserve Deck, reshuffling as necessary (if you are unable to deploy the North Ridge, you may not deploy the Main Power Generators). The same holds true if you select the Main Power Generators as your starting location.

When the Main Power Generators site is face up on table, the energy shield covers all Hoth sites except the outermost exterior marker site and the Wampa Cave. At shielded sites, the Dark Side may not:

• deploy vehicles, starships or characters (not even spies);
• take off or land;
• use shuttling, docking bay transit or any other movement that logically would be stopped by the energy shield (such as Elis Helrot or Bombing Run); or
• add power to battles as a result of starships controlling the system (e.g., from the Hoth system location, a Victory-Class Star Destroyer or Fear Will Keep Them In Line).

The energy shield does not protect the Light Side from a ground assault "underneath the shield." At shielded sites, the Dark Side may

• move vehicles and characters from site to site;
• deploy and use creatures, weapons, Effects, and other cards normally; and
• perform any actions not otherwise prohibited by these rules.

The energy shield does not restrict the Light Side in any way (because conceptually the Rebels can activate and deactivate the shield to allow their own forces to pass). When the energy shield is not active, both sides can deploy and move to Hoth normally.