particularly, when other Elf cards are played, theres an immediate bonus, and the fact that you can add any mana to it to then cast spells and activate abilities could make for a devastating combo, if played correctly
The list order is based on the market prices from TCGPlayer.com, which are subject to change
And lastly, dont forget that you can use Draftsim's Sealed pool generator to practice the set before attending your prerelease
In other words, if you cast Bloodbraid Elf with Flash during your opponent's End Step and flip into an Ichor Wellspring, you can cast the Ichor Wellspring (though you'll draw the card off the Wellspring's Enters effect before the Elf resolves!)
None of the people I frequently played with, at school or elsewhere, had any cards from Arabian Nights, much less a rare oddity like the ring