how to defeat myrida she is really hard all my pets r lvl sixty and at the highest equipmenti can get. plz help

So about your gear...

Mitsukokami needs a new relic. It's great that you gave him an evoker relic, but it gives him physical damage, which he can't use since he is stacked to use magical damage.

Same thing with Prince Glacia but in reverse... his relic gives him magical damage he can't use.

It's hard know what else is going on without knowing your proficiencies and so forth, but that should at least help you do more damage. Don't forget to use Mend whenever possible and bring potions! I don't really remember fighting Myrida though so I'm not much more help than that - but it's good I don't remember her, it probably means you can beat with her fairly easily once you change out your relics!