"That which blessed life upon to you shall also be that which will cast the shadows of death upon you."
Void Staff is an advanced item in League of Legends. It is used to counter champions that stack  magic resistance.
Damage % increase by target magic resist when applying 35% magic penetration
Combining with Void Staff yields 38. Devastating Strikes 9% magic penetration, rather than 41%, because percent magic penetration stacks multiplicatively.
The 35% magic penetration from becomes more effective the more magic resist the enemy target has on them. Ranging from 30 magic resist to 200 magic resist, the magic penetration increases damage from 8% to 30%.
Percentage Magic Resist penetration stacks multiplicatively with others champions percentage Magic Resist penetration abilities.
Magic penetration reduced to 35% from 40%.
Void Staff is now applied before flat magic penetration.
Coloring changed to blue from the glitch where in the shop it was red.
Passive ability is now Unique.
V184.108.40.206: Mid tier ability power/mana Item: gives your spells 40% magic penetration.
Jungle items and their enchantments
Boots and their enchantments