Another element of these battles is a building and fortification aspect similar to tower defense titles. Players can use resources taken from crystals scattered across the battle map and construct different types of fortification and buildings, ranging from defense structures to structures which offer player advantages or can be used to directly attack the enemy. During battles, players can also use special structures to summon allied monsters into the battlefield, granting advantages in battles. Later updates added new building types, weather effects, and additional levels of factions for players to interact with. In-game items can be earned, or bought for real money at a dedicated shop.