The Force gains +2 levels of Advantage at the start of every battle it is part of that occurs in a Desert Region.
When the Force is defending within a Plains or Desert Region and is not benefitting from the Fortify or Defend Actions, its attacker does not gain the normal +20% Combat Strength Modifier that it normally would from attacking within a Region with one of those Traits.
The Force does not suffer any of the normal damage from ending the Round in a Desert Region.