I thought I would post what I learned as a result of trying to collect Baium's blood for the subclass quest to help other people prepare themselves for this most joyful of experiences. This discussion is relevant for C5 only. The good news is that Baium is now so hard he does not appear to be farmed as soon as he spawns. This means you are very likely to be able to port in to see him on your first trip to the Angelic Vortex. It used to be very hard to get in to see him and people had to camp out the angelic vortex for hours if not days.
1> Be sure to select the "for the money" option in the Arrogant Search quest so that you can more easily get more than one Blooded Fabric [you must have a blooded fabric quest item to teleport inside the room with Baium, the Angelic Vortex on ToI14 is what you use to do this]. See below for why you will probably need more than one.
2> Make sure you have full buffs before teleporting in to see Baium. In particular, you want anything that gives you Pdef, Mdef, and Accuracy [you have to hit Baium with a dagger so any accuracy boost you get will help].
Then be sure to activate a Charm of Luck [just in case]. The person waking up Baium might as well strip just to be sure since they are most likely going to die anyway. The person that needs to complete the quest should wear good armor and jewelry [but may want to equip something they don't fear dropping].
I used the Charm of Luck and did not drop, nor did my friend drop [and we both died twice, since I had to visit Baium twice to get it right :(]. However, some people claim that the Charm does not work on Baium and I have yet to see an official response on this.
You will want to put a few things on your hotbar: attack action, quick healing potion, BSOE
The person waking up Baium should run over just in front of him. The person doing the quest should not be in front of Baium but also not too far away [more on this later].
3> Become friends with someone willing to die for you. When you port in to see Baium someone has to wake him up. You wake him up by entering into a dialog with him [i.e. you don't do damage to wake him up, you have to talk to him]. After you wake him up you can try to run away from him, but as soon as he wakes up you will be teleported back in front of him and he WILL get the first hit and this first hit will very likely exceed 1M damage. This means the lucky individual waking up Baium will very likely be killed. [Note that I have talked to people that claim they were not killed on the first shot but it seems very low probability to survive].
4> After your friend wakes up Baium WAIT. DO NOT run up to Baium to attack him - he is standing on a step and you CAN NOT hit him while he is there. Conversely, he CAN and WILL hit you from that blasted step [I learned this on my first trip to Baium :mad: hence my need for more than one Blooded Fabric].
After Baium wakes up he will most likely kill your friend. Then he will come off of the step. At this point a bunch of Arch Angels will spawn. The angels are there to kill Baium BUT they are also glad to kill you! After all, you did wake up the demon. They do hit pretty hard [about 800 damage to 600 Pdef]. This is why you want QHP on your hotbar. Pop these liberally as you run up to attack Baium. You won't get many chances to hit Baium. He hits hard [about 1500 damage against 600 Pdef]. As soon as you see the yellow text indicating you received the quest drop you should BSOE to avoid death.
5> If you or your friend died you can log out. Then if you wait about 20 minutes or so and log back in to the game you will still be dead, but in Aden [I did not confirm this part]. This gives you a chance to use a BREZ.
Hopefully this helps others out as they plan out this part of the quest. Good luck!