Each unit in "Wesnoth" has its own strengths and weaknesses. A unit's defense (which means in this case dodge chance) is based on the terrain it stands on. Elves, for example, are difficult to hit when fighting in a forest. Different types of attacks (melee and ranged), weapon types (pierce, blade, impact, arcane, cold, and fire), and a day-night cycle (in most maps) that alternately favors lawful and chaotic units, altering the amount of damage a unit deals. Units can advance to higher level counterparts and become more powerful as they participate in combat.