I appreciate that the proc is restored on the Mythical version, but did the proc really need to nerfed to oblivion at the same time? The 18.104.22.168 nerf was warranted in my option as it was a bit to OP with 50% Fumble/Impaired Aim
on a near permanent basis. This nerf on the other hands results in it being weaker then comparable items and even epic items.
Those examples you brought are proccing once every few seconds, attempting to apply the debuff once every time they proc.
Mark drops down a pool that attempts to apply fumbe/IA every second. Since it has twice the duration than it’s cooldown, it could overlap and go up to two attempts/second.
It’s much more reliable this way so the lower %chance compared to them is somewhat warranted.
The miasma robe one works this way too and has higher chance so it’s indeed stronger, but the item overally is much weaker for it’s slot than MotF.
They actually buffed it, imo, with the Bloody Pox buff and old Toxic Cloud back it’s a proper top tier relic now. I tested it today on my Vitality caster/Doom-Bolt Conjurer and it’s a great piece of equipment. Making Fumble’s chance higher would make invincible in Crucible, I think it’s fine as it is.
3 of the other items are on hit/block procs, and 1 is a manual cast. In contrast, Mark of the Forbidden is auto-proc on attack, and is the only one of the group with additional skill modifiers to boot.
All 4 of the so-called alternatives combined are far less popular than Mark of the Forbidden, so that makes it clear which items have truly been “nerfed to oblivion”.