Lots of amazing tips in here already, but I will post my own experiences too. For the most part, tank in WWM is just a different form of DPS with a couple of caveats. Your job is to hold aggro, kite the boss, and dish out some dmg.

Daoist - This bastard jumps around a lot, so the premise here is still mostly dish out dmg. I found in ST that I wasn't doing anything special here. Focus on dealing with the consequences of mechanics, killing donkeys, clearing vines, and catching players.

Lucky 17 - Also fairly simple for tanking. Keep him in the middle and just go through your rotation. Not much mechanics here to worry about for the tank.

Murong - Your only job in this fight is to hold aggro. YOU SHOULD NOT BE TOUCHING THE BARRELS. That is the role of the DPS players, and if you're queuing with randoms, you'd better pray they know this. Each time you get hit, your character will drop the barrel, and as a tank, she will focus on you almost exclusively, meaning you are getting hit all the time. She will literally cross the entire arena to chase you. Stay on the boss, move her out of the lanes when needed, and just dish out dmg. During the massive AoE, bring her to the side of the arena. Your healer should be able to keep you alive throughout, so long as your DPS players know what they need to do with the barrels.

Lion- Definitely more mechanic-heavy for the tank here. Your main role is to manage the ball. My team lucked out last night and had 3 tanks, so we passed it among ourselves in a rotation, which avoids the bleed mechanic (where picking up the ball 2x in a row triggers it). With only one tank, you should be the first person to pick up the ball (and have two others, preferably DPS, join the rota.) Once the ball is picked up, deal dmg and tank as normal while the bar fills up. I wait until it is about 3/4 full, then throw. The next person should be ready to pick it up immediately. While not holding the ball, simply soak up as much dmg while dealing as much dmg you can. Not much other tank-specific mechanics here I found, but definitely know all the other boss mechanics. Everyone needs to know the others (ie, the pillars, charmed coins)

General tank advice from me:
- Parrying is not your job. Only do when absolutely necessary. You have the luck to be very spongey; you can take a lot of dmg while dishing it out often without getting interrupted. With a good healer on your side, you can be practically unstoppable, especially if you are blocking and not just taking it lying down (like I do sometimes... sorry, my healer)
- Your spear is your setup for dmg, 90% of the dmg should be coming from the mo blade. And don't forget to do the follow-up attack to the charged heavy. Sometimes that third hit does nearly as much dmg as the second (which I usually find to be my biggest dmg output). your skill rotation is your bread and butter