Hello comunity... I want to ask you about two of my usually used champions.
Vladimir and Sona.
I would like to ask you... are they viable in a dominion match? Wich items would help me? Summoner spells?

Usually I play Sona as a support... with items that help my allies, with actives and passives abilities (runic bulwark, zeke´s herald, will of ancients, locket of the iron solari, etc) but sometimes I build her as a AP caster... but I think it's not a very viable option... lol

Vladimir, I build him just like another AP caster... but I want some suggestions that you can give... plz?

I really like Frozen Fist on Sona.
It gives her some nasty poke and extra utility, as well as making her a bit tankier and giving her CDR and mana to spam with.

If you want a pokey support that builds AP, grab Nidalee. Sona is -not- the way to go there.

She works best as an aura bot with 1-2 items that do some kind of damage and then building a bunch of tanky auras. I haven't played Sona since S2 but I'd imagine the way to go wouldn't have changed much other than there being upgrades for Aegis and Sheen now. Something like ...

Boots/Double Ruby
Sheen
Sweeper
Aegis, upgrade when MR is needed on team
Iceborn Gauntlet
Abyssal or Zekes depending on team comp
Giant's Belt into FM or Randuin depending on if more kiting or combat utility is needed.

Order is totally dependent on the match but I'd build Sheen/Sweeper/Aegis before the rest.

I can't give you any help with Vlad, I haven't played him since everyone and their dog picked up Executioner's as an AD and blew his sustain to bits.