I find it very hard to justify getting Sunfire - I even thought this before Ciderhulk was a thing.
Why get
when you can get
which is a far better item for increasing your effective HP against Physical Damage. Couple its superior stats with its Cold Steel Passive (which stacks with Frozen Heart's Aura by the way) and its Active, I see no reason to get Sunfire Cape.
Out of all of the Tanks we've been seeing lately, I can't think of one who doesn't have sufficient pushing power with their basic abilities in combination with the CDR from
and
which most Tanks should be getting anyway. No, seriously. Maokai, Sion, Mundo, Gnar, Shyvana, Hecarim, Irelia, Renekton. The list goes on and on. They have wave clear for days. If anything, Sunfire limits your pushing power because its Aura draws turret aggro.
I would maybe, MAYBE get it as a situational pseudo-offensive item to stack its Magic Damage with
, but even then I'd probably prefer
or even
.
If I were to rework Sunfire Cape, for Argument's sake, I'd probably do it alongside a Soft Randuin's Omen Rework.
Sunfire Cape
+
+ 800g =
(2850g)
+500 Health
+70 Armor
UNIQUE Passive - Cold Steel: When hit by basic attacks, reduces the attacker's Attack Speed by 15%.
UNIQUE Toggle - Immolate: Deals 2/3/4/5% Current HP as Magic Damage per second to nearby enemies (Maximum Damage to minions: 25 + 1 per champion level). Immolate can remain toggled as long as its charges remain. 1 charge is consumed per second, and 1 charge is restored for every 2 seconds that immolate isn't active. % Current HP increases at levels 1, 6, 11 and 16.
Randuin's Omen
+
+ 800g =
(2850g)
+500 Health
+70 Armor
UNIQUE Passive - Cold Steel: When hit by basic attacks, reduces the attacker's Attack Speed by 15%.
UNIQUE Active: Slows the Movement Speed of nearby enemy units by 35% and the Attack Speed of nearby enemy units by 15% for 2 seconds (+1 second per 200 Armor and +1 second per 200 Magic Resist). The Attack Speed reduction stacks with Cold Steel Passive (60 second cooldown).
This would create clear identities for each item, as well as introduce decision making when choosing items as the Cold Steel Passive is Unique.

. But even then, Randuin's Omen, Thornmail or even Zhonya's Hourglass are all also suitable options/
(your standard first items if you're building a Bruiser or Off-Tank).
who can use their gap closers to get into the middle of the Enemy team and then use its Active to slow the whole Enemy team.
, more movement speed at a lower cost :)
with something like 