The best way to figure out what a good buy-in will be for a given box is to become familiar with the market trends of booster boxes overall
Today, it is a key piece of the Yawgmoth combo deck in Modern, 4-Color Elves in Pioneer, and a fun card for many Commander decks
If Weeping Angel would deal combat damage to a creature, prevent that damage and that creature's owner shuffles it into their library
Removal is so good in limited, even five-drop removal spells see play, let alone strong two-mana ones like Candy Grapple, so draft players running black must take cards like this right away
Burn to race If you are playing a deck with burn spells, there comes a time when you need to decide whether you are playing to race or playing to control the board
Maybe you prefer the Modern incarnations of mill and hold your Hedron Crabs and fetch lands very dearly