You can manifest any card, and a poor draw could mean terror with no payoff, but typically, it will be a creature card that gets manifested, and that means a surprise beastie to fend off
The card had some decent hype behind it when the set came out among Commander players and you'd see it a pretty fair amount
Even with its single ink cost, this is still two cards youd need to invest in that can easily be replicated by the likes of Brawl or other early game board removal staples like Let the Storm Rage On
You can burn though a good chunk of your deck this way, letting you pick and choose which cards to keep depending on the situation
until the end of turn, you can cast that spell and spend mana of any color to cast it
Big Score/Unexpected Windfall [c]Big Score[/c] (or [c]Unexpected Windfall[/c], which is basically the same card) are like the previous entry, but with the additional upside of creating two Treasure tokens