There’s no guide explicitly for zekvir yet, I was going to actually beat it first before I wrote anything. Twin’s sun priestess works on brann because he acts as a party member. Improved silence didn’t feel particularly necessary in regular delves and brann can be extremely annoying positionally so I like to have life grip to get him back near me when he decides to run away like a coward. It’s also useful on the zekvir fight to grip him out of angler’s web if it’s going to kill him (Or to grip him into angler’s web if he’s infinitely feared and you need him to die to reset it.)
When I killed it I wrote a full Zekvir “??” guide and posted it on the forums. I’m in the process of transferring that information to its own guide page on wowhead as we speak.
I’ve also just found a video of someone using that guide to get a kill themselves.
https://www.youtube.com/watch?v=SJEUwYxTNVY
Hope it helps people.