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Question about magic penetration

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Cat 6th

Senior Member


Do more items like haunting guise stack, for example: i get the sorcerer boots (passive +20 magic pen) + haunting guise x3 (passive +20 magic pen) + void staff (40% Mpen) + abyssal scepter (+20 Mpen aura).

This should be +20+60+20 flat Mpen, and 40% Mpen. But it seemed to be like haunting passive don't stack each other.. can explain please?

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Emissary of the League


Abyssal Scepter is Reduction, not Penetration. There are several key differences, but yes, they all stack(ish).

Currently on live, the order they are applied is:
% Reduction > Flat Reduction > Flat Penetration > % Penetration.

Reduction actually reduces the enemy's current resistance (Armor or MR depending on the type of reduction), whereas Penetration 'ignores' it (acts as if it wasn't there). There are two key differences here, the first is that Reduction can reduce their Armor or MR to negative values, actually making them take more damage than the unmitigated damage. (This is hard to do, the main thing to note is that Penetration cannot do this, so having 20 Reduction and 40 Penetration against a target with 30 MR is wasting 30 of your Penetration.) The other aspect is that since Reduction actually reduces their Armor/MR, they take more damage from your team as well.

Also, Haunting Guise's passive is 'UNIQUE,' meaning you cannot stack the passive from that item multiple times.