Among the best box options you can consider Dragon Shield Fortress Card Drawers or Ultra PRO Magic: the Gathering Mana 8 Dropship for large collections or Gamegenic Cards Lair for smaller collections/grouped cards
The Spear of Leonidas (the card Kassandra searches for) is a great Equipment as well, giving you a versatile tool depending on the game state
This is the card you want to open at Prerelease, not least because its probably the biggest bomb in Bloomburrow Limited
This is to say that, despite the cost that each draw minimally impacts the composition of the rest of the deck, this deck probably has better mana than a 60-card deck with one less color (Im not sure how problematic needing to fetch four colors instead of three will actually be to how games play out)
While killing a ton of your opponents stuff, then spending five mana for this is difficult, using sacrifice outlets and drawing cards off that seems much more realistic
Now you'll exile three cards from your library instead