Items that can be helpful :
Warmog's
Banshee's Veil
Will of Ancients
Void Staff
Mobility Boots
Ninja Tabi

Reason why i have Rod of ages is because of the Mana and Health it gives you and also the passive.

Try using majestic roar if the minions get close to your tower and use frenzy if your some where in the middle of your lane. If you cant really farm in early game try at mid game or Jungle a bit.

The spells i would take for Volibear is Flash and Teleport because his slow at the start. Other spells i would use sometimes are Heal & ghost or Exhaust and Ghost.

If you get into a team fight you should use majestic roar and your ult if you have it you should be able to tank the attacks from enemies and your health regen should help you . If you get a 3v5 or anything like that try to use Shurelya's Reverie active passive to escape if they come chasing try to use majestic roar and rolling thunder to help your team mate escape even if you die.