Campaign Mode strategy: This is where the maps start to get larger in the game. Still at two Heroes, up to this point, you are left with the same strategy. 2 choke points for both lanes, 3 cannons, and 1 archer tower to get rid of the enemy volume from afar. Fully upgrade your cannons first with the rockets to target the enemies even from afar, followed by the archer tower. Reserve and make use of Fee’s wolf on the 3rd wave when the bandit shows up. If it cannot be helped, build a barracks near him to help get rid of him. Near both entry points, put up an additional cannon and a barracks as choke points. Fully upgrade your barracks to get your units more resilience to the volume of the enemy waves on the 5th and 6th wave. Do not let Lancelot’s defense buff go to waste. It might not look much, but this is plenty to do the work and get you the 3-stars.
Legendary strategy: Have 1 barracks protect each of the base points in the map, and the rest, build an un-upgraded cannon. Put efforts on securing cannons on the left entry point first as the first leg will surge from here. As soon as the right entry point spawns a monster, secure cannons on the middle lane and the right side of the map (see the picture for final build). Have Lancelot secure one side, and the other two Heroes (and the wolf) for the other side. Upgrade the middle cannons when possible.