The Wizard is an Elixir Troop unlocked in the level 7 Barracks. He is a fragile ground unit with high splash damage and range.
Wizards are commonly used in large groups for fire support or as a force multiplier (similar to Archers), but they can also be effective in smaller numbers, especially at lower levels.
Wizards have no preferred target when attacking; they will simply attack the closest building. However, if they become aware of enemy Clan Castle troops, Heroes, or Skeleton Trap skeletons (either by being attacked themselves or by being near another friendly troop under attack), and can fight back against them, they will leave their previously targeted building and instead engage the enemy troops.

The Balloon is the sixth overall Elixir Troop unlocked in the Barracks, and is the first aerial unit unlocked in the Home Village, requiring a level 6 Barracks.
Balloons are "promoted" Wall Breakers that now attack from a hot air balloon. They drop bombs towards the ground within a large area splash radius, dealing heavy damage, which can destroy a wide range of ground targets, but can be easily taken out by any anti-air buildings or air-targeting splash-damaging buildings (such as Air Defenses, Wizard Towers and Scattershots).
Balloons have high damage for their housing space, but low attack range and rate. They also cannot hit air units.

The Wall Breaker is the fifth Elixir Troop unlocked in the Barracks once it has been upgraded to level 5. As its name suggests, Wall Breakers favor going after Walls, dealing massive damage to them.
The Wall Breaker attacks by locating the nearest protected (read: Wall enclosed) building and destroying its protective Walls, blowing itself up in the process. It deals splash damage around its target and deals 40x damage to Walls.
Wall Breakers prioritize Walls above all other targets, and will completely ignore any building or enemy troop while even a single segment of Wall exists on the battlefield.