Area-attack is one of the 5 character Battle Types. They offer wide range of AoE skills to deal with many enemies at once, although their skills possesses great area to hit, they are less useful when there is only one target. This type of heroes got large scale of mana and most of their skills are less consuming.
Most Area-attack type characters are good on being a PvE hero rather than a PvP one.
There are 5 types in total in the game, you can see the others here: