After some exploration and riddle-solving, we came across the witch of the swamp, an annis hag, I think. She dropped a fog cloud that she could see through for some reason, so I cast blade ward and shillelagh and boldly went forth despite the mist. Armor of Agathys was already in place. She grabbed me and did 32 damage which netted me a loss of one hit point, then I was grappled. I think she was resistant to cold, but took some damage which was important later when the ranger actually started hitting (colossus slayer). But prior to that, the party rather ineffectually tried to attack her or capture the child-turned-raven that was the object of our quest.
I tossed my staff of the python onto the ground to summon Chokehold, figuring I might end up going down. On the hag's next turn, she dropped me to 3 hit points. More ineffectual attacks from the rest of the party followed due to the fog cloud. I tried to escape the grapple, but failed even with Inspiration, though it was close. She fell just short of the damage required to kill me outright at the start of her next turn. The bard and ranger worked together against the hag and a combination of a decent roll and bardic inspiration let the ranger finally land a blow. The hag failed her Concentration check and the fog cloud vanished. That's when Chokehold grabbed her as I rolled a 1 on my first death save...
The nature cleric rushed to my aid and brought me back up as they started to focus attacks on the hag, now with advantage, and the hag's counter attacks at disadvantage. It wasn't long before we took her down. As a result of this turn in the story, Bogg Rumble's weakness was revealed in the bard's songs: Hugs.
So, I think this build did as advertised, even in the short time we played. I soaked up a lot of damage, dished it back, and kept the rest of the party's hit point pool in a good place. In a longer game, this character could conceivably do a lot of encounters in an adventuring day.
Thanks for the help!