I pety much ifnored this move but it's quite good.
In mazes you can avoid geting mobed just by jumping on empty platform and whn mobs jump after you you do ground slam and knock them off-then you can just keep it up till their hp reach 0.
Good vs boses too-you knock boss down with it and when it tries to get up you ground slam it back down-eventuay boss will use a skll and counter it but untill than you do good damage-a lot beter than using firebolt and circle.
in pvp it works quite well on knights-they just charge at you-you goround slam them and then emediatly do a grab when their stuned-it ither reduces hp to 0 or to a very small amount-depends on level and equips-but still very damaging combo.
the only con is that you have to press z multiple times.