GAE expands on the leveling system. Units can level after specified numbers of kills. Normally units all gain the same stat boosts each level, but with custom leveling, you can choose which stats you want to boost and by how much. Levels can boost stats two ways, either with a static number or a multiplier. There are also more stats that can be modified now. For example, one unit might only get faster as it levels up, or they may get EP so they can use a new attack, etc.