with Sion you have 3 options
solo top
Jungle
or Adc bot
this guide will only focus top and bot

follow the above biuld and warmogs is the troll item

all you need to do is farm
with sions enrage just use it to farm minions hard core. your creep score should be 200+ by end game. this ensures that combined with warmog's that your health reaches 4000+ in any game even though your biuld is adc/ lifesteal fighter

always remember to stun enemies under your turret
kill them then if you can. this opens up farming opportunities. if you are 1v1 at top, then you can farm freely.

never go bot unless you have proper support like a warder and healer
when going bot, the build is the same except you are melee adc
a way around hateful teammates is to have a real adc mid and a mid laner that can go top
and your tank will jungle this works out if you talk it through with your team. I did this with rengar but we had another fighter top so we were lacking a real adc with yi mid xin as fighter in the jungle and some top dude cant remember