Just base lines. Not going to give exact stats or gold costs.
Unique passive immolate - reduces ap of all enemies in range by x amount increasing to a cap. (Takes sunfire passive away)
Unique passive thorns - when taking physical damage, reduces the attackers attack damage by x amount increasing to a cap (takes thronmail passive away).
Both items have trade offs of losing other core items, both help tanks actually be tanks.
Both also wouldn’t be too crazy to implement due to them having pre existing mechanics tied to them.