ALRIGHT. So most of this is going to be speculation but I'd like to just discuss it nonetheless. We know for a fact that Araxxor is solo/duo, obviously, and it has 23 mechanics. You can "build the boss" to your taste - which mechanics and when - depending on three different routes you take.
Basically ... here's what we know/what I'm speculating.
http://puu.sh/ahsWs/2046cdc860.png - from the btw
http://puu.sh/ahsWs/2046cdc860.png - from me exploring lol.
(getting closer since my computer is crap) - http://puu.sh/aht5x/dfc61c9097.png
In the BTS, is shown a wall. South of the wall is a large group of plants, along with a cave. In the first screenshot of me exploring, the mushrooms there are where the cave will be. The cave will be shown by my marker in the next screenshot - we know the location for a fact.
Exact cave location http://puu.sh/ahtel/a5aac80350.png
From the BTS, you can see the "achievements," some of which include healer/acid (http://puu.sh/ahtjv/837b436f6d.png)
1. Healer/Destruction - Seems to heal based off the "eggs" that drop from the ceiling in the video, also only takes place while in the area where the ledge falls off and the spider goes to the ceiling. (http://puu.sh/ahtqP/910ea279de.png)
2. Acid - Shown the most in the video, corresponds with the "achievement"
3. No idea as of now
Finale - Burning the webs in the area, might use all mechanics from all 3 routes?
Mechanics that I'm speculating (not posting as many screenshots here)
First of all, Araxxor uses all three combat styles. You can see the bottom of his legs + back change from red (melee) to green (range) to blue (mage) throughout the video. So sell wand.
1. Swipe - occurred during melee phase, assume thats the only phase it will occur in. Swipes a large section in front of him, preparing for the attack he pulls two of his front legs back. Escape/surge away
2. Encased in webs - Does consistent unblockable damage, seems to only occur during mage/range phase, heal up before it happens or possible bcade? Might happen a lot, not sure if blade would be worth it.
- for whatever reason, this seems to deal more damage towards the end, where you might have to freedom to break free?
3. Minions spawn
4. Eggs drop from ceiling (healing route only?).
5. Entire body burns green/something to do with acid?
6. Charge attack (much like KK) happens during melee phase, might happen during all 3, seen in what seems to be the healer/destruction route. -- go under the charge? http://puu.sh/ahwoe.png
7. Web cage? - seen very briefly towards end of video - possibly something similar to barricade/KK (Anarchy Time)
8. Standing together (duo) to either block damage or prevent healing, something in between. Seen (http://puu.sh/ahu0P/550ac60f4c.png)
9. Spitting? Idek. http://puu.sh/ahu0P/550ac60f4c.png
10. acid lul
11. environment breaks down around you
12. burning webs possibly during final phase