You can let the whm doing medica II, it's enough for the party. If you know the fight and with good use of ogcd, you can do it without brd/mch. I've done it multiple times with my Whm Ilvl 190 (My partner was a sch). The whm can also dps if he mh the first part (20k damage before the split) and keep everyone alive. Just a bit help for prey. Your whm can use Benediction 2times, the fight is like 8min XX sec.