Viper skill page is a complete mess.

[ShaolinMike]

TBH, it's really not necessary to even pay attention to the skill page. I just used the skill names to figure how to set up my crossbars:

1. Skills ending with "Fangs" are your single target combo buttons.
2. Skills ending with "Maw" are your AOE combo buttons.
3. Serpent's Tail is your oGCD button after combo finishers.
4. The "Dread" skills are your Darth Maul combo starters (Dreadwinder single target; Pit of Dread AOE).
5. Twinfang and Twinblood are your oGCDs in between your Dread 3-part combos.
6. Uncoiled Fury, Serpent's Ire, and Reawaken are self-explanatory.
7. Writing Snap is your "I screwed up and have to peel away from the boss" ranged failure attack, never to be used.

That's really all you need to know in terms of setting up your bars initially. You may want to adjust for comfort once you unlock Reawaken.