First try to buy Belt for get max health and tank easy almost any champ.(if any stun first get it and only then use fear and drain)
Then If vs you alot ot ap or ad get first resist then try to ges as can fast hour glass it's help too survive all cast of your ulty and only then get some ap you will easy tank for your team.
When you get Belt and hour glass take your range champ of you team and go take Baron it's will be easy. Usualy i get it at 17-20 minut.
Rylai's Scepter are good if when you ulty all enemy champs run away from you. If then soo stupid use hour glass and you kill them almost all easy
When will have time chenge Chapter