Archer Towers are extremely versatile structures. They are able to target both Ground and Air Units, and they have excellent range. This versatility means that they should form the cornerstone of every player's defense.
Archer Towers can target both Ground and Air Units at an amazing distance. Therefore, it is generally a good idea to place them on the outer perimeter of the village. Doing so allows players to capitalize on the excellent range and provides good coverage for the rest of the defenses.
As Archer Towers have the ability to target both Ground and Air Units, a good strategy would be to place all of the other defenses within range of at least one Archer Tower.
It is typically a good idea to upgrade Archer Towers before you upgrade Cannons. Although they are more expensive and take longer to upgrade than similar-level Cannons, Archer Towers have more range and can target air units as well as ground units.
It is typically wise to put an Archer Tower near a Cannon or Mortar due to the fact that neither of these two structures can target air units.
Their ability to target both Ground and Air Units makes Archer Towers formidable attackers. However, Archer Towers are only able to damage one unit at a time. This makes it very easy to overwhelm them with large groups of Archers or Barbarians.
When deploying only a few Balloons, it is advisable to keep them away from an Archer Tower, as their slow movement speed makes them an easy target. However, Balloons deployed in large numbers will quickly destroy an Archer Tower while only losing one or two Balloons. After the Archer Towers (and Air Defenses) are taken out, the Balloons will proceed to destroy the rest of the village (although Wizard Towers can still be a problem). You can also place a group of Archers (around 15-25) and let them do the work.
Archer Towers undergo significant visual changes at levels 6 and 12.
When initially constructed, the Archer Tower has an open wooden lattice supporting a flat wooden platform; an exterior wooden ladder leads from the ground to the platform level. From levels 2 through 5, the lattice structure and wooden platform both receive additional reinforcement.
At level 2, the Archer Tower gets 4 short posts on the top.
At level 3, the Archer Tower gets gray stone paddings on the legs and the short posts connect each other.
At level 4, the Archer Tower has the paddings turn into supports.
At level 5, the Archer Tower gets stone walls connecting between each support.
At level 6, the lattice supports and exterior ladder is replaced with an interior staircase and solid vertical supports. The wooden platform receives stone battlements.
At level 7, the interior staircase is blocked off by a stone wall.
At level 8, the Archer Tower receives a green flag on each side and metal at the bottom of each leg.
At level 9, the Archer Tower's flags get longer and the metal on each leg turns into spikes.
At level 10, the flags get larger and golden plates get placed around the whole tower.
At level 11, the color scheme completely changes, and the battlements receive dark iron shields on each corner with stone skulls in between them.
At level 12, the tower gains golden guard shields on its bottom and golden spikes all over it with silver corners at the top, and shoots fire arrows.
The number of and apparent level of the Archers atop the tower also change with level.
When first constructed, the Archer Tower has a single Archer on its platform, with the appearance of a level 1 (or 2) Archer.
At level 8, the Archers' appearance changes to that of a level 5 Archer.
At level 11 and 12, the Archers' appearance changes to that of a level 6 Archer.
You don't need to train an Archer to have the Archer Tower, nor do you need to unlock the Archer in your Barracks. Any upgrades to Archers you have completed in your Laboratory have no effect on the Archer Tower whatsoever.