a lot of ppl think lightning is op but actually his damage isnt that greater than u think it is in terms of total damage. Aoe damage, fire mc's, mei's aoe does more damage than lightning. just lightning mc is specialized at one target and it may kill one ninja out that will break ur balance is kinda issue.
also u notice that mystery is always faster than auto att.
if you have a concern, just build ur team that can endure first round.