Mine was almost exactly the same, Rebel Moon! My Durge was a vengeance paladin / lore bard, who honestly felt like a swiss army knife in terms of usefulness (she could heal, tank, damage, buff, debuff, handle locks and traps, etc). Wyll was in the party 100% of the time once he joined and Karlach 80% of the time. The last space was broadly for whoever seemed most appropriate - but sometimes a second different character would need to be rotated in, hence giving Karlach a few short rests.
I was very happy with how this team turned out. Karlach is naturally a very reliable source of damage, due to reckless attack. I made sure that Wyll was similarly reliable by giving him the risky ring so he always attacks with advantage (plus the daredevil gloves, so he could cast easily in melee too if needed). Both of them also turned out to be very tanky, with Karlach's bear aspect giving her resistance to most damage and Wyll frequently getting temp HP due to landing the final blow on enemies. Wyll additionally has so much utility with spells like invisibility, hold person, and gaseous form. Now don't get me wrong: any situation is made easier by having Shadowheart cast Spirit Guardians and run around. But Wyll and Karlach are super-effective too.
