Notes from author
Well DkS 2 PvP sucks, so I'm going back to DkS 1 with my new PvP build.
31 Intelligence because you'll get your 5 Homing Crystal Soul Arrows. 42 poise because you can't go to 41, and 41 helps agianst double katanas/straight swords/spears one-handed attacks. It also helps poise through the Black Knight Great-axe one-handed attack.
The basic strategy is to combo off using your Magic, i.e. Great Chaos Fireball into WotG into backstab into Black Flame. This is by no means easy, as you have to time the combo to pick off an opponents' mistakes, so going all aggro on an experienced opponent is just asking for an ass-whooping. Play defensive (never attack randomly) and only cast when they approach you mercilessly, and from there you can usually cast a Great Chaos Fireball on the ground or something and perform the combo mentioned.
A few other combos can include:
--> Great Chaos Fireball into Fire Tempest (cast Fire Tempest on the larva to avoid getting punished).
--> The combo mentioned before. It's the most lengthy combo but one of the strongest. Can possibly be followed up with more casts/a swing of your sword if you're fast enough.
--> WotG into a backstab into Black Flame. You can cast WotG with your back facing your opponent for the best use.
--> WotG into a Black Flame. This is a safer version.
--> Backstab into Great Chaos Fireball or Moonlight Great-sword two-handed special attack.
--> Moonlight Greatsword two-handed special attack into WotG into a backstab into Black Flame. You can substitute the Moonlight Greatsword's special attack for any Great Chaos Fireball (except for the Fire Tempest combo). This is useful because you might run out of casts.
There are many other combos, especially ones involving the Moonlight Greatsword's normal attacks (depending on poise breaks). I'm not claiming I'm the creator of these combos, I just came across them personally. You can use other weapons if you wish (to abuse that high dexterity stat).