I certainly try to be more careful in environments where mistakes will be more costly
It's just that useful--so long as you're still drafting blue and black
Xira, the Golden Sting, Massacre Girl, Known Killer and Kelsien, the Plague have slightly different methods of marking a target, while Vraska, the Silencer, Vein Ripper, and Twinblade Assassins are assassins which simply incentivize murder regardless of any prior mark
This is among the most powerful things you can do in competitive Magic and has made blue historically the strongest color (which becomes more apparent in formats where cards from the 1990s are legal)
Well, promotional foils are worth a column in their own right, and they have a lot in common with original set foils, but theres one big difference