Quite simply... any Shifter that is next to the Void Knight protects the Knight from ranged (Defiler) and mage (Torcher) attacks. The East and West Portals usually get taken out first, which leaves the Southwestern and Southeastern Portals to keep spawning monsters. This being the case, the South Gate usually ends up with tons of monsters waiting to get in or fire long-range attacks at the Void Knight. By leaving any Shifter that is directly to the South of the Void Knight, those Shifters act as blockers from any missile attacks. Once these Shifters get killed by some unknowing fool, we notice a barrage of Defiler and Torcher attacks upon the Knight, usually ending with said Knight's sudden and painful death, as well as a failed mission. (And a few people muttering a few choice words about "some noob this" or "some noob that". So, please leave those Shifters alone! Also, another piece of strategic information... If we concentrate our efforts on the Portals (and the Spinners that occassionally pop up), it is possible to be victorious in less than 2 minutes from the start of the mission! Good luck and happy Pest Controlling!