There have been cases of some players painting, writing things in the back of their cards to identify what they draw from deck
Goblin War Strike and Mob Justice are almost identical in function: For one mana, they deal one damage to an opponent for each Goblin you control
When Cartouche of Zeal enters the battlefield, target creature can't block this turn
Cephalopod Sentry has power equal to the number of artifacts you control, Broodstar gets the same amount of power and toughness, while Shambling Suit looks for artifacts and enchantments
Some want Commander staples
MTG, for the first time in its history though not completely unprecedented, as WotC from the TCGs earliest years had to deal with the moral panic over satanism in the 90s