The Wizard Tower is a spiraling cone-shaped tower of crystalline rock that has a Wizard atop of it. It is capable of inflicting powerful splash damage to both Ground and Air Units, but incapable of dealing damage over a large range.
The Wizard Tower, like the Mortar, excels at mowing down groups of Troops. However, unlike the Mortar, it puts out a decent amount of DPS (damage per second), and will also target Air Troops in addition to Ground Troops. Also unlike the Mortar, the Wizard Tower has no blind spot.
Although the arcane blasts from the Wizard Tower do less damage per shot than Mortar, it makes up for this by having a much higher rate of fire than the Mortar. This makes the Wizard Tower an excellent choice for defending other structures by blasting troops that get too close. The Wizard Tower's only real weakness is its range, which is among the lowest of all defensive structures.
Wizard Towers and Mortars are very complementary; as they both have specific weaknesses that the other unit can address.
Taking out Wizard Towers can be tricky despite their relatively short range. It is often a better tactic to avoid them entirely by attacking another part of the village that isn't covered by them. To quickly destroy a Wizard Tower, deploy a few Giants as a distraction while Archers, Wizards or Minions take out the tower. Deploy Troops in a circle around it since this will limit its ability to take out multiple troops with splash damage. Dropping 1 Giant and 5 Archers nearly always works (assuming they are of comparable level to the Wizard Tower).
An excellent defensive strategy for the Wizard Tower is to put it near your Town Hall because of the Wizard Tower's splash damage and relatively high rate of fire. However, due to its limited range it is sometimes more desirable to put the Wizard Tower near the outside of your village.
Another good strategy is to put it near your Mortars, as both cover each other's weaknesses and can decide the outcome of a raid (see Wizard Tower-Mortar combination example below).
Putting your Wizard Tower next to your Storages is an excellent way of protecting them against hordes of Goblins due to its splash damage and fast attacks.
It is helpful to put Mortars and Wizard towers in range of each other.
Example of a Wizard Tower-Mortar combination: The Mortar can cover a very large range so attacking units will have reduced health by the time they come into shorter range of the Wizard Tower, which helps finish them off. In exchange, the Wizard Tower defends the Mortar by destroying units that cannot be attacked by the Mortar (all air units and ground units inside the Mortar's minimum range).
For attacking, use some units to distract it (Giants, or Barbarians if necessary) and destroy it with Archers or another ranged troop. Melee troops like Barbarians or Giants can destroy a Wizard Tower by themselves if there are enough of them, but because these troops must attack while physically touching the tower (and are therefore grouped up), the Wizard Tower can attack the entire group simultaneously.
When deploying units, be careful to ensure that they won't get into a clump as they come into range of the Wizard Tower (for instance attacking a Gold Storage near a Wizard Tower), because the Wizard Tower will destroy the group very quickly.
Wizard Towers undergo significant visual changes at levels 2, 6, 7 and 8.
When initially constructed, the Wizard Tower appears to be solid gray rock.
At level 2, the lower portion of the tower begins to show Elixir-colored pink crystal, much like the level 6 Walls. This can be seen if you look closely enough, and can be easily missed.
At level 3, the crystals become much more visible.
At level 4, the crystalline structure begins to spiral around the tower.
At level 5, the entire base of the tower is completely crystalline, with only the top portion of the tower remaining gray rock.
The level 6 Wizard Tower has no gray rock left. The entire tower is now constructed of pink crystal, resembling a gigantic level 6 Wall.
At level 7, the crystal structures grow prominent upward spikes, and the entire tower darkens considerably to appear very much like a giant level 7 Wall.
At level 8, the podium of which the Wizard stands on becomes far wider and more jagged. The spikes are more melted into the tower and it has stone pillars on each side. It also has embers floating around the base, indicating a lava source beneath.
The Wizard atop the tower also changes with the Tower's level. Although its physical appearance changes, it always shoots lightning bolts (regardless of what the Wizard unit that it resembles would use).
When first placed, the Tower Wizard appears as a level 1 (or 2) Wizard.
At level 3, the Wizard atop the tower changes in appearance to that of a level 3 (or 4) Wizard.
At Wizard Tower level 5, the Wizard changes its appearance to that of a level 5 Wizard.
At Level 8, the Wizard changes its appearence to that of a level 6 Wizard.
You don't need to unlock or train a Wizard in order to construct a Wizard Tower. The level of your army's Wizards, if you have them, do not affect the appearance or abilities of the Wizard atop the tower.
When you upgrade the Wizard Tower, the Wizard on the top will disappear after a few minutes and will not reappear until the tower has finished upgrading.
When viewing the Info screen, the Wizard Tower does not have a Wizard on it.