Three-mana planeswalkers arent supposed to invalidate creatures, artifacts, and win conditions all at once, but Oko didnt get that memo
2 Non-foil borderless or extended-art rare of mythic rare cards This can be one of the 43 borderless rares (46.2%) or 17 mythic rares (9.2%, including 5 borderless planeswalkers)
Further Upgrades The first cards I'd pick up to further juice up the deck would be untapped mana-fixing lands: Watery Grave, Shipwreck Marsh, Underground River, Morphic Pool, Darkslick Shores, Polluted Delta, Sunken Ruins, Undercity Sewers, Urborg, Tomb of Yawgmoth and then maybe a couple more Island / Swamp fetches
It is exciting to see it evolve during our time playing Magic
Or maybe it did, depending on your slant