White has an abundance of narrow tutor effects, and thankfully, you can make great use of them here
For example, in Urza's Destiny (the set where I was the entire design team), there were two different cycles that explored effects that scaled based on how many cards of a certain color were in your hand
Demonic and Vampiric are better but the Vault does have advantages over them and is not that far behind in power
Book Devourer Borrowed Knowledge Brand Break Asunder Breakthrough Byway Barterer Canyon Crab Careful Study Carnage Interpreter Case of the Crimson Pulse Catalog Cephalid Sage Ceta Sanctuary Chains of Mephistopheles Chakra Meditation Chandra, Flame's Catalyst Chandra, Flamecaller Change of Fortune Choking Tethers Claws of Wirewood Clear Clive, Ifrit's Dominant Cloud of Faeries Complicate Compulsion Conqueror's Foothold Contract from Below Control of the Court Cool but Rude Coralhelm Chronicler Cram Session Customs Depot Dangerous Wager Darkwatch Elves Death Pulse Decaying Time Loop Dirge of Dread Disciple of Grace Disciple of Law Disciple of Malice Divide by Zero
Ignoring the hexproof rider, this is basically a Trailblazers Boots that draws you a card on attack in the right deck
