Skeletal Scrying combines the black use of the graveyard with the Necropotence effect (paying one life to draw one card) to provide the cheapest X card-drawing spell this side of Prosperity
At the beginning of your end step, if you gained and lost life this turn, create a 1/1 black Bat creature token with flying
Open it if the chase suite and pack experience matter
add 1 "Void" Spell/Trap from your Deck to your hand, except "Void Vanishment" or "Null and Void", also you cannot Normal or Special Summon for the rest of this turn, except "Infernoid" monsters
Add to all of this the fact that the card has no retreat cost, and you have one of the most impactful cards in the competitive meta for the Pokmon TCG
This sometimes evolved into awkward yet funny moments where players had to fail-to-find their Wish effects, so to speak, while others lamented having lost gold due to the bug