Great Chaos Fireball in NG?

[DaltonGoesFast]

I am on my first playthru, and I was wondering how many PVP matches I have to play to get the pyromancy from the PVP leader? Also, what are the best magics to use in the game? I am INT/FTH so I use great heal, great heavy soul arrow, dark ball, and great fire orb. Am I missing anything really useful?

[JellyPuff]

It's a Rank 3 reward, 500 Points for BoB Rank 3, +1 point for a win and -1 point for a loss at BoB arena. In other words: Minimum fights required = 500, maximum number of fights required = ∞
You'll also get +2 if you kill a Blue Sentinel summoned through the Way of Blue covenant to help a host that you invade, but that scenario is just not gonna happen.

In other words, buying from Wellager on NG++ infinitely faster, than grinding 500 points on BoB arena, especially without some PvP experience. Or just use Forbidden Sun.

[Flre]

noone can tell you exact ammount of matches, because it depends on your winrate.
if you are winning every single fight (100% winrate) it will take 500 wins to reach rank 3 in bob. If you have 50% winrate you will never get that Great Chaos Fireball. With 60% winrate it will take 2500 games to achieve that

Originally posted by JellyPuff:

You'll also get +2 if you kill a Blue Sentinel summoned through the Way of Blue covenant to help a host that you invade, but that scenario is just not gonna happen.

Not sure if that statement is true, because wikidot says:
"Please note, killing Blue Sentinels when they invade your world is not a valid way to gain prestige points in Brotherhood of Blood. This has been confirmed with Bandai Namco support."

[TrueArchery]

Blue Sentinels that invade you =! Blue Sentinels that are autosummoned by Way of Blue members when you invade them

Getting GCFB in any reasonable amount of time is not realistic period. Especially if you aren't very experienced. Just forget about it, the only viable way is going about halfway through NG++ and buying it, like a couple of other covenant spell rewards.
That being said, you can buy one scroll in every following NG+, too, so if you run through the game a couple of times you will have a couple of them. Shouldn't have to be said, but Ascetics don't count at all.

The best spells differ for each encounter and your exact build. Generally sorcery and hexes are fine (Soul Spear and Dark Orb are the best all purpose spells, good damage/number-of-casts ratio and accessible), pyros are held back a lot by their few casts and so are miracles until you have a ton of Atn and multiple Great Lightning Spear scrolls and such.