I noticed 
gives some nice mana regen, bonus health, and a powerful active when playing Support. But Shurelya’s is almost never a recommended item on pro builds sites.
When should I get this item? Is it especially good on certain champs? (I noticed quite a few Rakan players building it as a second core item)
Thanks
I believe this item is good on supports that are buying athene unholy 
because of mana regen synergy. Its stats are really good for Janna because her ability requires movement speed. The active itself is definitely good if you have Hecarim 
jg or Twisted Fate 
mid because the movement speed helps a ton in catching up to champions that are trying to escape
You can build it on 
.
I like it on 
as a last item.
When you're playing Spurm build TF.
