Towers are powerful items that can be placed in an area to help you destroy your enemies.  

When you equip a tower, you must first progress through the areas to charge it. Once you've charged it enough, you can place it anywhere and it will help you.

You can only place one tower at a time and once the area is cleared, the tower will disappear. You will then need to recharge it before you can use it in another area.

There are different towers that look different and work differently.