If a musketeer king poisons enemy cells off the edge, you don''t have to kill them to move onto the next area. This is great for the 2nd area, but also useful in areas 1 and 3 as well.
NOTE: If an icewind is poisoned off the edge you still have to kill it! Do not let your musketeer kings poison icewinds in the 1st or 3rd area it could slow you down!