(Reminder text is any italicized text in parentheses that explains rules you already know.) Can Duh destroy a creature if another version of it exists with reminder text
Doctor Doom, King of Latveria is a 3/3 creature who costs four mana (1B, 1R, 1U, 1C) and whenever you discard a land card, each opponent loses two life
Excess damage is dealt to that creature's controller instead
While Ob Nixilis is at its best in decks like Rakdos Sacrifice that can reliably produce expendable Creatures to use for its Casualty ability, there are other cards that are decent even without taking Casualty into account
Demonic tutor kind of defeats the purpose of a restricted list if you can just tutor the restricted card
More than 2 Cards: In very very rare cases, a card can get misaligned on 2 axis (horizontal and vertical) and get miscut in a way that shows more than 2 cards