Spreading Seas is one of the best ways that blue can shut down specific lands, and it really doesnt show up often enough in Commander
You've spent the mana to cast the spell, but instead of putting it on the stack, you're placing it under Ice Cauldron
If you do, you'll have to choose if you want to keep these cards in your hand and pay 4 life for each one of them, or just put them at the top of your deck
Wizards wants you to be able to play all the cards, and demanding ones like Corpsejack Menace and Lessons from Life go sour if you're missing a color
And then yours is doubled, so I like her as a midrange white Commander leading with ETB stuff like the recursive Sun Titan and card draw in Inspiring Overseer and removal in Loran of the Third Path, and then triggers like Soul Warden and Angelic Chorus
Neither deck will get you there by themselves, but they both offer a good base and color wedge to start building your competitive Commander deck around