Black Mage Sanctuary - A Guide to DPS

[Galvuu]

snip

I got this on Reddit too... there's something about the Foul placement in the rotation (especially the 3.X one) that people forget.

Where you cast Foul has huge implications on your overall pps (and, by consequence, dps) of your overall rotation.
On your UI cycle, you have the options of casting the T3 dot (which, depending on clipping, is likely gonna net you 300+ potency) or, if you're lucky, a TC proc (500+ potency, again guestimatng for clipping), Blizzard IV (the most horrid pps out of all our viable spells) and Foul.
You need to cast two things in your UI cycle to get your whole mana back (save for server tick nonsense).
This means that if you don't cast Foul in your UI cycle, whatever spell you replace it by is going to yield a massive loss in pps in your UI cycle and, by extension, your whole rotation.
This is why casting Foul in your AF rotation is terrible (aside from AF refresh issues)- it's terrible because now you're forced to shove a crappy filler on your UI cycle that brings your whole pps down (because you need to wait those two ticks).
The fact 3.X can afford to bypass B4 and go T3>Foul in UI is why it yields higher pps.
This is also why you use the 4.0 rotation when you have whatever necessary cooldowns available- to ensure you realign your Foul clock so you can Foul on every Ui cycle of your 3.X rotation.

If you want to think the way you are thinking, then you need to push that idea all the way- account for all spells in the entire fight.
If you Foul out of UI alignment often, at the end, you'll have a bunch of B4s and Blizzards and overwritten T3s and other useless nonsense.
A person who doesn't will have instead a bunch of Fires and Fire IVs.
Aka: a person that uses the 3.X with Foul only and 4.0 when they won't get Foul/Foul is sure to not be ready on the next UI cycle will slowly push ahead a pps lead over the whole fight.

Now you can say "well, ok, so I just B4 as filler if I don't have Foul and go into 4.0". Exactly- that's why you compare both with Foul.
That's why you use 3.X if you have Foul (on the head-to-head with Foul available, 3.X wins) and 4.0 otherwise (out of necessity, but it's surely convenient that it has a slight pps lead).
Further, you can make it so that you only use this 4.0 thing when you have Triple (Triple makes 4.0 beat 3.X in pps by a hair). Using it this way also reduces its vulnerability to mechanics, so it all wraps around very nicely for us.

This is all consequence of the fact that you need to cast two things in your UI cycle, and all non-Foul options are utter rubbish.

tl;dr: don't think of Foul in a vacuum. Understand that whenever Foul is available for UI the 3.X rotation yields higher pps, and when it's not you do the 4.0 both out of necessity (B4 is the only realistic filler spell) and because it also has a very slight pps lead over the 3.X one without Foul. Bonus points because you can align Triple with it every time.