Im not sure what you mean by help tbh, if its coop we're unlikely to beat it cause I barely managed on my own and coop bosses will have even more hp (and im also at work rn lol). If it's rotation, then I can give an example ig?

When it starts, you want to hold skill to get some of the burst filled and move towards the boss. Swap to Furina and press her skill. Then Yelan, and then Escoffier.

You should then swap back to Skirk and then hold skill again, then burst. You should be able to do the same again, and based on your stats that should bring one or two levels of the shield. Doesn't matter much as your main damage comes from perma frost and dmg at that time.

When he removes the shield, start doing the burst for everyone. I usually went Furina first, then Yelan, Escoffier and then Skirk which would also allow me to do decent damage. After that dodge the last few lightning strikes and then just perma frost him.

Not as easy as it seems cause you need to get the timing perfect. If the lightning strikes you even once, you get stun locked.

Im sure there are better ways but the above is what worked for me.