You have to be good at farming to have any prayer of making this work. If you're not, just go to some other roflstomp guide and practice csing, then come back after more practice. Don't be afraid to use abilities if it means getting farm, especially your w and your ult with farm.

Pros:
Kassawin screw you rito
Impossible to gank post lvl 6
Mobility
Your ult's mobility
Tanky aaaaand bursty
Very snowbally build
ap shield with low cool down
mobility
mana sustain especially late
mobility

Cons:
Can be shut down early
Farm and Item reliant
Expensive build
no cc (rip silence)
his aoe slow essentially needs to be charged
very mana hungry early

Please don't do this in a ranked game until you've done this a few times.