BIS Viego?

What do you consider BIS on Viego?

Scizors make Viego Titanic, activating the +1 starting Mana. They also let you duplicate a Mist, which grows Viego, the Mists, and everyone else if you have the 6* Power.

I’m not sure about the last slot. Spellweavers Symphony in SI gives you a lot of slay spells, but you dilute the pool by adding other champs/different regions.