Join Shields $0.09 Join Shields is fairly expensive as far as protection spells go, but the untap clause eats the occasional attacker, and you cant beat countering a board wipe for less than $0.10
There are tons of little details in this card too, that you might miss if you dont pay close attention to it
If I were to guess at the Soulcaller's best home, it would either be in an aggressive Boros Weenie list or possibly even Naya
As such, for today's ranking, we only consider cards that spell out draw in their rules text
If you already have the Science
You can do some interesting things using effects like Sword of Hearth and Home and Bazaar Trader, the latter of which can give you a treasure for passing on something you already borrowed, and making sure it never goes back