Suggestion to Buff Sunfire Cloak:
was hit pretty hard by being nerfed, but then was made less important to many of the champs that previously built it such as
and
in favor of
which has comparable stats, but also an undeniably amazing and unique passive that grants mobility.
My proposition would not make it unique among all items, but mainly among non-boot armor items. What if we give
the passive effect of Furor/Rage? It is a very hard effect to work into AP bruiser's builds such as the deceased
or the still serviceable
and
without taking
on boots. I think that giving it this passive will allow it to be the AP champ's mobility armor competitor against the AD champ's
.
Other champs likely affected by it:
,
It would also make an option for melee AD champs that do not want to build Cleaver.
Admittedly the prime candidates for why this is a bad idea are:
,
, 
But
needs a looking at to make it compete better in some way, this is just one possibility.
Edit:
I think it would be an important part of its balance come to think of it that neither [Chainmail] or [Bami's Cinder] provide PhageRage as you try to build the final item unlike [Cleaver] . This is also similar to how [Giant's Belt] does not provide mobility before you make [DMP, aka the Department of Mobile Platemails] as well. Adding this to OP.
To say that the power spike provided by either is not provided at all until the item is complete, like most defense items. Unlike offensive items that do something mid-way like
or
itself.
and, technically,
. There are a ton of AD mobility items such as
,
,
,
or
provide PhageRage as you try to build the final item unlike
does not provide mobility before you make
passive,
,
, and
do affect it already.