Spell vamp - unique?

I don't really understand the unique-ness in LoL. Is it per item or per passive type? It doesn't seem like the internet fully agrees about this (it's not clear to me at least).

If I have both the Hextech Revolver (Unique: +12 % Spell Vamp) and Will of the Acients (Unique: +20 % Spell Vamp) will my spell vamp be +32 % or 20 %?

Solution 1:

Uniqueness works in a couple of ways. If an item is unique (without a name, like Will of the Ancients (WOTA) or Hextech Revolver) then it will stack with each-other, giving a total of 32% in your example. However, if you upgraded that Revolver into a WOTA, your spell vamp will be only 20%. This being, if you have multiple of the same item, the unique effects will not stack. (Look in Youtube for examples of people stacking the Sunfire Cape in old Seasons - wreaked havok Like this one). Some items, like the Sheen / Lich Bane / Frozen Gauntlet / Trinity Force combo, have a name associated with the unique effect (called spellblade, in this instance). Uniquely named effects like so will not stack under any conditions.

TL:DR -

• Unique stats will not stack ON THE SAME ITEM (ie 2x WOTA), but are ok with two different items
• Items with a Unique - name skill will not stack under any condition