Mikoto help?

is it good ? no sadly, but it does useable.
you can refine her flash, and make her opener for your team, if your team is a PP unit.
disabling counter attack is pretty good.
the standard build would be wrathful/dazzling on B slot, then refine your weapon with the other. but it's expensive, since its 5* locked skill.
for budget option you can always run her default kit, B slot can be stuff like live to serve from wrys, or breaker skills.
with bow breaker she can be your Blyn counter too.
or Guard B skill also work, so she wont trigger enemy special when trying to disable their counterattack.