As with so many of the great card-draw spells it only costs one mana, but it gets a little bit more complicated after that
I'll have to give the answer I was given when I met Jim Henson (back in my Hollywood runner days) and asked if Bert and Ernie we're named after Bert and Ernie (the cop and the taxi driver) from It's a Wonderful Life: It may very well have been but no one remembers doing it consciously. Farewell to Arms In Unglued , black had a theme of forcing your opponent to restrict himself physically
To start with, the promotional card is not just a simple freebie
Those rocks don't do much on their own, but you can equip them to Akiri and remove them to deal 2 damage to any target
There are cheaper and less vulnerable ways to give your creatures haste, although I suspect that no one is attacking Samut because they dont see it as that big of a threat
This effect is great for lots of Rakdos focused cards that care about casting spells from exile or if you are playing Ob Nixilis, Captive Kingpin in the Command zone