Just took 2 hours or so to spec into Protection Pally and solo Plaguefall on heroic to earn the
Slime Serpent mount. (As of Summer 2021, you had to solo all four bosses instead of the last two.)
I am a decent iLvl (i245 as pro pally) so that helped because I don't have much experience with the toolset -- although after today I am getting really familiar with it. In fact, I now get while the pro pally can interrupt a lot -- one of the regular hotbuttons is a shield that auto-interrupts anything it bounces off when cast. (This is in addition to the regular interrupt + the stun.)
The trash was pretty easy overall, aside from an occasional scare moment. Tanking was like I remember for my old guild in Torghast the night they needed a tank -- I can soak a lot more damage than I can as Ret Pally, I just can't do nearly as much damage.
- Globgrog -- pretty easy mechanics wise, just took awhile. I learned fast to also cut down the slimes when he calls them, because if they reach him, they heal him back up with whatever health they have left.
- Doctor Ickus -- I knew how to clear all the trash easily from running this dungeon as DPS. The biggest deal is the Slime Injection, which I forgot about, and I must have pulled a few stacks and then just croaked before realizing it. I think I took him on the second or third try. I can soak a lot of the explosions when needed, but was popping some CDs when slime injection took over.
- Domina Venomblade -- Fairly hard but routine. Either she or Ickus was the hardest of the bosses. I took her on the third try, and by then I got into a routine and was just making sure I popped CDs to minimize problem areas, Blinding Flash to momentarily stun assassins, and always was grouping up the assassins as soon as they appeared as well as prepping for the 2.5 second stun (capping health, popping a CD) that I could not avoid. It took me awhile, maybe 6-7 minutes when I finally beat her? I actually was able to use Avenging Wrath 3-4 times in this fight, despite its longish cooldown.
- Margrave Stradama -- Take out the trash group with Ickor Bileflesh last so he can't port around. // Damn, I don't know whether this was because I did it so much on Mythic + or whether it's just a far less deadly dynamic, but I aced it on first try despite mucking up one or two tentacle whips. The tank can actually take a tentacle whip on heroic without too much damage. Just tank the add when it appears until it dies, soak the puddle, CD the rain, and keep whittling the Margrave down... and then just pay attention to the tentacles and don't botch avoiding them too much. The only "eh" moment is when if you go too long multiple mechanics are in play (she stays and does attacks, while tentacles come out). But honestly, I think it might have been the easiest fight of the entire dungeon.
There was a benefit in terms of solo tanking, because I didn't have to worry about other players and could dodge some of the mechanics rather than having to pop CDs to take them in the face.
When you are done, you just warp back to Domina Venomblade's location and in a pool off to your left is the slime serpent waiting for you to click on it. Easy-peasy. It's just as a Prot Pally, it takes awhile because of less damage. I'm impressed with the folks who ran it at level 210-220 after all four bosses became mandatory, but I think they were tank mains so they knew their toolset well and were specced for it.
The slime serpent is the Nzoth serpent mount from BFA, just in icky green colors like the Maldraxxus constructs (you can see the stitching down its sides). But I think it looks kind of cool. It has spikes and seems like a giant organic bramble.
Ironically, this mount and one of the other serpent mounts are the ones I am most proud of because you can only earn both while soloing -- here by running Heroic/Mythic Plaguefall, the other one by completing both of Nzoth's nightmares (orgrimmar and stormwind) with five masks running. the latter one, I worked very hard when the patch was current and earned it the hard way; this was one was a little easier due to iLvl but not a walk in the park, and I still had spent some time learning the dungeon. Most mounts are just RNG tests and/or depend on a full group.