Am I the only one who just loves building RoA on pretty much any caster ? I built it as a first or second item all the time on champs like Ahri, Viktor or Cassiopea... gives them some much needed health while still giving a pretty good chunk of Mana and AP.
you're gimping so much of vik's potential not building pure ap. you can blow up targets so much better and get a bit more out of shield that way. You should be able to manage your mana fine without roa. Cass is understandable since shes sustained damage. Makes me sad when I see viks rush roa as it stunts his strongest part of the match (mid game) but delaying so much for such a costly item