In Pauper, your four-mana spell better get you close to winning the game (see Tendrils of Corruption or Guardian of the Guildpact)
Small details like the energy symbols, the Pokdex entry, or the card number can be telltale signs if they deviate from the standard format
Understanding how rare the grade is for that card adds context to the price
To back up this wincon I'm including a bunch of counterspells and to try to get to it or whatever else we need at the time, I'm running Vampiric Tutor, Demonic Tutor, and Mystical Tutor
Notably, Emrakul may be the target of a spell that targets it while on the stack, such as Convolute
Personally, if I want a specific card, i'll just grab it instead of buying and ripping boosters to get it