Also applies to these Incantations when cast with other Seals, as long as a Frenzied Flame Seal is held in the other hand.
The main upside of the Frenzied Flame Seal is that it has no requirements to wield and is weightless, making it useful for casting Law of Regression on a build with high Intelligence but no Faith. It's also the only Sacred Seal that scales with Dexterity.
Since Faith is the strongest scaling stat, leveling the other three stats do not provide big benefits.
Note that though it's Incantation Scaling scales with all four of Strength, Dexterity, Intelligence, and Faith, it's low scaling in all means it doesn't stand out unless only Faith is low among those stats, as the Godslayer's Seal and Erdtree Seal will strongly outmatch it with a decent amount of Faith, and the Golden Order Seal will quickly start to catch up at high Intelligence as long as its minimum Faith requirement is met.
The Madness from the Seal is only applied to its melee attacks.
At maximum upgrade level it has 119 Incantation Scaling with Strength, Dexterity, Intelligence, and Faith at 10, and 373 Incantation Scaling with Strength, Dexterity, Intelligence, and Faith at 80.
Has 170 Incantation Scaling with only one of the non-Faith stats at 80 and the others at 10, 201 Scaling with two of the non-Faith stats at 45 and the other two at 10, 221 Scaling with only Faith at 80 and the others at 10, 242 Scaling with Faith and one of the non-Faith stats at 45 and the other two at 10, and 325 Scaling with all four stats at 45, 271 Scaling with Strength, Dexterity, and Intelligence at 80.