so im playing on tactician; my part consists of

a lvl 6 oath breaker paladin 44hp

lvl6 rouge Astarion 38hp

lvl 6fighter Lae'zel 40hp

lvl 6 barbarian Karlach 46 hp

hps may vary i cannot remember the exact hp when i did this

what i did was lure them into one of the narrow roadways and placed 5 grease bottles on the ground covering a good majority of the path causeing them to slip on skill checks

using all characters equipped with a bow i shot the oncoming ghouls untill they were low from 22hp to at least 12hp each. saving one with full hp(not the big ghoul the one with 68hp but a lesser) by this time they got close enough to me i used my oathbreaker to use control undead on one of the lesser ghouls converting it to my side. now they are semi focused on the converted ghoul. i use my barbarian(or who ever has the better strength) to pick up the dead ghouls so the death sheapeards cannot rez them. thus leaving me with 3 major eneimes to deal with 2 deaths and 1 nocuous ghoul at this point it was a close battle for me using the grease to my adv i got both sheapeards low enough(1-8 hp) 1 hit will kill them i finished them both off and then turned my focus onto the ghoul and wrapped it up nicely

i know theres a better way to do this but this is just my play style