Depending on the format, you can use your trusty turn-1 Llanowar Elves to set up your future plays, or you can use cards like Elvish Archdruid and Priest of Titania to produce tons of green mana depending on the number of elves you have on the battlefield
See their post here: I find it a bit unusual that they decided to ban cards that were so popular and have been around for so long, but they offer a pretty good explanation in the article: its experimental
This opens up the door to a huge array of powerful combos, but its completely viable in fair decks as well, easily ramping out a power play or two on Treasure mana alone
Sacrifice Cover the Spot, then open an Attraction
You cast a second Shadowspear, and the spell resolves
the other face's characteristics are ignored