Pyromancy damage doesn't scale with any stat, however it does benefit from the casting speed increase of dexterity. At the casting speed cap of45 dexterity your casting speed will be roughly 15% faster (spell dependant) this means it synergizes well with high dexterity builds. Good weapon choices include the Balder Side Sword, any curved sword (My favorite is the gold tracer, the gold streaks make it look like it's on fire), Life Hunt Scythe and Great Scythe, Katanas, and sometimes spears. However, from a pvp perspective, pyromancies don't have a lot going for them. Mostly I stick to Black Flame for guard and poise breaking, as it's a very fast casting short range spell that does Ultra great sword damage. The spells that summon pillars can be used to bait someone at a distance into running in for a backstab, only to get caught up in the storm. And any spell with "Chaos" in it's name leaves little puddles if lava that are okay at catching people rolling towards you or turtling behind a shield off guard. But you know, if you're going for a dexterity build, the flame weighs nothing and you can get a few attunement slots on any starting class for 3-5 points. So why not?