the short answer is that only Crushing Flames Set affects Crushing Blow damage.
the long answer is…
Crushing Blow is % chance to take 25% of the enemies current HP. as the enemies HP goes lower, less HP is taken.
Normal enemies:
1,000,000 hp -25% =
750,000 hp -25% =
562,500 hp -25% =
421,875 hp…
as you know, other damage is being done, so the HP would be even lower. theoretically, if you have 1 to 3 HP, Crushing Blow stops working, because damage is done in whole numbers, not fractions. but even the weakest level 1 weapon with only Crushing Blow would kill a monster when it gets down to the last few hundred HP before CB could get the HP down to 1-3 HP.
for those wondering why Crushing Blow doesn’t work as good against Blue+ Tier monsters, it’s because CB’s effectiveness is reduced.
-25% for Normal Monsters
-6.25% for Magic Monsters (0.25 x 0.25 = .0625)
.25 x .25 x .25 for Rare Monsters
and so on for Epic, Legend, and Mythic monsters.
Crushing Flames Set increases Immolate Damage by +25% per Rank and increases Crushing Blow Damage by +50% per Rank.
the average Player usually has Crushing Flames (5) for +250% Crushing Blow Damage.
.25 x (1 + 2.5)
.25 x 3.5 =
CB with CF (5) does -87.5% of Normal enemies current HP
CB with CF (6) does -100% of Normal enemies current HP
1,000,000 -87.5%
125,000 -87.5%
15,625
.0625 x (1 + 2.5)
.0625 x 3.5 =
CB with CF (5) does -21.875% of Magic enemies current HP.
I don’t know if this is true, but in Patch 3.1 or later, there was a discussion about CF (6) being nerfed to put Normal enemies HP to 1 instead of 0. this was because on higher floors, builds with Crushing Flames (6) or higher with Frozen Set (5), when Instant Killing Normal monsters, caused insane amounts of damage on Pack Size Maps with monsters in big mobs. this went against Crushing Blow only taking 25% of enemies current HP and only being affected by Crushing Flames Set, because it was also affecting Frozen Set.
1,000,000 -21.875%
781,250 -21.875%
610,351.5625… since there is no fractional damage…
610,352 or 610,351 (because I don’t know which way fractions are rounded)
Crushing Blow and Crushing Flames both work in Battle Arena. Players are considered Tier 3 (just like Rare Tier monsters).
that is -1.5625% of a Player Characters current HP.
-3.90625% with Crushing Flames (3).
also, because Crushing Blow & Crushing Flames reduces an enemies HP to 25% pretty fast but also causes a lot less damage, Demonic Set and/or Execute affix are used for the other damage to do 2x damage to enemies with 25% or lower HP.