Terrain is the background appearance area where a battle takes place. Depending on a character's abilities and the terrain type, the character may get a boost when fighting on certain types of Terrain.
There are two types of cavern terrain. One is the Caves, which usually appear as the terrain for any quest that takes place in Maze Pass. The other is known as the Ruins terrain, mostly used in clear quests, but also used for the Ancient Ruins in the Lake of Sand and the Titan's Cave in the Mystic Mountains. Aina and Marga both have abilities that boost their stats when fighting on this terrain. The barricade of Cave terrain is a cluster of stalagmites, while the Ruins has stone barriers with wood in front of them.
Desert terrain has only one version. It uses spiked palisades as the barrier and is covered in sand as the name implies, the background consists of several sand dunes. It is almost exclusively used as the main terrain in the Lake of Sand region. Jafarr, Raheem, and Gizgo benefit from this kind of terrain.
Forest terrain currently has only one version. It is covered in a large amount of trees which almost nearly obscure the sky behind it. It is mostly used for battles in Soul Island and the Mystic Forest, but sometimes also used in certain parts of Sage's Tower. Celeya, Phillip, Paboa, Tornado, and Raioh all benefit from this type of terrain.
The Plains is the most common terrain that appears during battles, no one currently has a boost from it. It is known for its grassy ground and having some hills in the background, the barrier behind your squad in this field are spiked palisades. There are two variations of this terrain, day and night.
Sea terrain was added in the version 2 release of Chain Chronicle. Areas that are near or on water are categorized as sea terrain. Four variants of this terrain type exist, the ship and the beach variants, which both also have day and night versions. Currently, only Peixe receives a benefit on this type of terrain.
Snowy terrain is the rarest terrain so far. The only constantly available quest for it is "The Spark of Battle" from the Flame Sprite Colony. It has what seems to be ice-capped mountains in the background, and uses a spiked barrier covered in snow. Only Popra benefits from this type of terrain.
Urban terrain consists of three different variants. One of them is the street, which has a couple houses in the background along with a church and a few market stalls covered by sheets. Another one is the interior, which seems to be a lavish hallway with a reflective floor that lets in light through its windows and uses the remains of a marble column as a barricade. The Street and City types are most often used in quests involving the Vice or Holy Capital. Ioh and Michidia receive boosts when fighting on this type of terrain.
Wasteland terrain has two different variants, one of which is a foggy and barren landscape, and the other, known as the battlefield terrain, is the same landscape on fire. Both variants are commonly used for the terrain in the Nine Territories of Fire and the Royal Capital. Sakon, Oguma, Semial, Haruka, and Whargman all benefit from this type of terrain. Although Demon Raids have this appearance, characters and abilities releated to Wasteland, do not change during the Raids.
These types of terrain are only used in certain occasions and usually aren't accessible in any of the free quests.