i just go to the swamp water well take the hp buff cast Aid spell. With those two it's easy because you need that hp buffer.
After you survive a failed initiative rolls with all that Hp you just smack them around.
Without those two buffs it can happen that you will lose one guy to the burst damage. Pets can help with that as well, if positioned correctly. The key is to have one guy in threat range of the crossbow guy at all times pets work as well.
The only thing they have going for them is the 2 attacks.. After one dies the fight it pretty much over can be done without consumables and dips.
Of course you can just ignore that rule and use pots and scrolls, poison, skip the cutsceen and just start the fight from stealth and preplaned location but that is just cheesy.