public Creep getCreep(){
        int ID = (id-1) / 3;
        int creepId = (id-1) % 3 + 1;
        if (ID == 0){           //air
            return new AirCreep (creepId);
        }else if (ID == 1){     //water
            return new WaterCreep (creepId);
        }else if (ID == 2){     //fire
            return new FireCreep (creepId);
        }else{                  //earth
            return new EarthCreep (creepId);
        }
    }