Hey every one this is Tapeofducks and im doing my very first guide for LoL. I'm doing my guide on my favorite champ Amumu, The sad mummy... This guide is PROBABLY NOT WHAT YOU ARE LOOKING FOR and your probably thinking.... DERP
(THIS GUIDE WAS WRITTEN WITH THE ASSUMPTION THAT YOU ALREADY KNOW HOW TO PLAY AMUMU)

simple... magic pen AP and manna re gen... need i say more?

9 x .87 + 2.01 = 9.84 magic pen (just in case you were wondering)
from the runes

see runes

9 x .87 + 2.01 + 8 = 17.84 magic pen (just in case you were wondering)
(8% of 100 = 8) from masteries

NOTE: assuming the opponent has 100 magic resist

see runes then refer to masteries

9 x .87 + 2.01 + 8 + 15 + 35 +20 = 87.84 magic pen(just in case you were wondering)
(15) boots
(35% of 100= 35) void staff
(20) Abyssal Scepter
NOTE: assuming the opponent has 100 magic resist

remains the same W,Q,E,R

Now for the main reason I made this build is because of his passive which lowers the enemy's magic resist by 35 for 3 seconds when you auto attack them. with that being said... your total magic pen is around 122.84 (note this guide was made at like 5 a.m. so my math is probably wrong and there's most likely a ton of grammatical errors!)

thanks for reading i hope you enjoy and i would love to hear feedback if anybody trys this build!!!
comments are a big help for me to see what i will need to improve on
Thanks again!!