Now that you've got Runo as the commander this should be a functional deck. The only real issue is that you're playing a deck with a high curve. It's an unfortunate downside that comes with playing a
sea monster deck. I do have a few other suggestions, but it's mostly just small changes at this point.
Your land base is solid. There are only two lands I'd remove:
Temple of the False God and
Vivid Creek.
Temple of the False God is really bad to have in the early game so it's a bit of a trap.
Vivid Creek enters tapped, so there's just better options. I'd replace these cards with your choice of either
Choked Estuary,
Drowned Catacomb,
Exotic Orchard,
Underground River, or just a basic land.
It's
a good thing you have a strong mana ramp package. You're going to need it. I'd still swap out
Burnished Hart,
Commander's Sphere,
Dimir Locket,
Sky Diamond, and
Solemn Simulacrum for
Coldsteel Heart,
Fellwar Stone,
Mind Stone,
Star Compass, and
Talisman of Dominance. If you have the money to spare you can instead use
Sapphire Medallion. If you want another effect like
Caged Sun and
Gauntlet of Power you can think about using
Extraplanar Lens. You're using enough basic islands to make it work.
You're going to want some more card draw. I think you're going to want both
Windfall and
Whispering Madness. They're both good card draw and you can take advantage of the discard effect with
Runo Stromkirk. You can also choose to use
Notion Thief. It lets you steal your opponent's card draw, and if you play
Windfall/
Whispering Madness with
Notion Thief on the battlefield you'll draw all the cards your opponent would have drawn while your opponents get nothing. That means you win. Far cards to remove I'd start with
Coastal Breach and
Devastation Tide. You already have a lot of boardwipes that will ignore your creatures (like
Whelming Wave), while these two don't.
After that the only thing left is to play some games and test this deck out. See how it performs.