The Nest is Caulder's base of operations and the central research facility for his organization, IDS. It is extremely powerful, with two tiles having the ability to build any unit for free, including Seaplanes.
The Nest is armed with 5 cannons, the far left and far right of which can rotate on 45 degree angles, and two mortar launchers, one attached to each rotating cannons. These weapons fire after Caulder finishes repairing and supplying units.
The lasers deal five damage to a straight line when fired, while the mortars will target the player's "most dangerous" 5-across group of units for 5 damage each, similar to Tabitha's CO Power.
By destroying all five cannons, The Nest will suffer a system overload and self-destruct, taking Caulder with it and instantly ending the mission with a success. As Caulder has no HQ to capture, this is the only way to win the mission aside from the much more difficult rout.
Lin will suggest in the Tactics Tent to effectively ignore Caulder's forces, concentrated on the east side of the map, and quickly sweep north to attack The Nest while capturing cities and production facilities rapidly with the pre-deployed Infantry. This is highly advised, as the lack of Fog of War and Caulder's CO zone effect make directly confronting his forces extremely difficult.
The cannons have 99 HP each and are vulnerable to direct attack only from one tile, the one directly below, so players must use Bombers and indirect units to deal this much damage before Caulder's units arrive to defend the cannons. Thankfully, the cannons do not repair damage.
The mortars cannot be attacked and will alternate between firing on the left and right sides of the map, starting from the left on Caulder's first turn. Therefore, keep the units on the targeted side spread out to avoid important units being damaged.
Two tiles, one on each side of the three central cannons, can produce any unit with no cost, including Seaplanes. The player cannot move on top of these tiles, but can siege or surround them to prevent Caulder from freely creating advantageous units such as Fighters and Seaplanes.
After a brief lull of peace, Caulder's eastern forces will begin to attack the player's bases, serving as an effective time limit for destroying The Nest.
Caulder reveals himself as a clone of the original, and the survivor of a war between all such clones and their creator. It is unknown if the original Caulder was as bloodthirsty and maniacal as his clone.