While doing my different builds for my AP heroes, I've noticed existing builds on the net sometimes (often) combine Sorcerer's Shoes
and void staff
, and I don't really understand why.
When calculating enemy's effective magic resist, magic resist reduction and penetration is calculated in the following order :
- Percentage magic resist reduction
- Flat magic resist reduction
- Flat magic penetration
- Percentage magic penetration
Meaning that if you buy both item, Sorcerer's Shoes
only give you 12 penetration if you have void staff
. It even goes down to (a little more then) ten if you took the Archaic Knowledge
mastery.
Another thing reducing usefulness of void staff is if the Archaic Knowledge
mastery. Percentage magic penetration doesn't cumulate, both penetration are calculated one after another: meaning 40% (Void Staff
) + 15% (Archaic Knowledge
) penetration only gives a total 49% (and not 55%)
So question comes, is it still a useful purchase ? Problem is there aren't many items that reduce or penetrate magic resistance (Abyssal Scepter
, Malady
, Haunting Guise
, Sorcerer's Shoes
and Void Staff
).
Several options come up :
- Purchase both items (and more if needed)
- Concentrate on flat penetration and magic resistance reduction
- Don't take flat penetration (too concentrate on CD reduction or more AP) and buy
void staff
- Try to compensate with runes the lack of penetration I may have if I don't take
void staff
- Ask for teammates to take hero with spells that reduce magic resistance
- Anything else
I usually abandon void staff
and work with Abyssal Scepter
+ Sorcerer's Shoes
, but I'm starting to feel it may not be the best option.