There's a mechanic in Final Fantasy XIV where you get 3 'levequests' every 12 hours that you can spend on quests for any of your classes. They accumulate so you can store up to 100 of them, and they're worth a ton of experience, especially for crafting. There's a terrible gating system on them though, such that you need to complete a combat levequest to unlock each of the levequest hubs. My Goldsmith level is 39 and my Miner level is 35. I want to do some of the 36-40 levequests, but I can't open the hub without a combat class of at least level 35. My Arcanist is 30 and my Marauder is 22 so there's a long way to go if I want to get there with my tank class. Ultimately I decided to get my Arcanist up to 35 first, unlock the levequests for my miner, and see where to go from there.
I posted earlier that I didn't much like the Arcanist, but after doing the level 30 class specific quest I unlocked a new ability which helps a lot. It can be used twice every 60 seconds and spreads all of my dots from my current target to all other nearby enemies. It also has a 15% chance to refresh the dots on my current target. So I no longer need to worry about targeting all the enemies in order and trying to track dot timers in my head. I can just target the primary target and chunk out a ton of damage to everything else at the same time. There are no damage meters, but I know I'm doing a lot of damage now compared to at level 29. I do wonder if I really sucked before, or if I'm really awesome now, but it doesn't much matter. Do more damage!
My main storyline progression was stuck at another dungeon, so I queued up for it while questing. I got in, blew some stuff up, but I kept pulling aggro from the secondary targets and wiping the group. Or at least that's what I thought was going on... It turned out the healer was lagging out, so the tank was actually dying shortly after engaging and then I had aggro on everything else and they would come and kill me. Once we recovered, I think because the healer raised the tank while I was healing myself while tanking all the mobs, so I didn't really piece it together. Eventually the healer disconnected entirely and the other DPSer gave up and quit at the same time. But we still had the tank so the dungeon finder thing got us replacements in no time at all. With an actual competent healer the rest went smoothly and I wasn't pulling aggro on anything, which was good. So I think the earlier problems were just tank deaths and not too much splash damage.
The final boss fight started with a wipe because I wasn't told what I needed to do despite asking before the fight. The second time I knew what to do, did it, and we wiped when the other damage dealer disconnected and we got overwhelmed by adds. At this point the tank gave up too. The dungeon finder found us a new DPSer in short order but no tank arrived for 15 minutes. At this point I started wondering if maybe I should just pull out my tank pet and try to go with 3 people, but I didn't know if the healer could handle that sort of thing. But then the healer suggested we try just that! Run it! 3 people, no tank... No problem! Well, minor problem, in that the healer couldn't keep us all together during the large numbers of adds phase. The other DPSer died, but we'd burned a couple down by then, and I was able to finish the rest of them off. So I ended up tanking the boss on my DPS class. Woo! Undoubtedly it was entirely thanks to the healer being awesome more than anything special that I did, but it was still pretty neat to have happen. I feel like none of the prior fights would have been a problem with a yellow Carbuncle tank either, assuming good play from the rest of the group. The dungeon finder certainly won't let me try it, but I think it might work with the people in our old World of Warcraft low level dungeon group.