To be honest, there should be another way of getting Lux out as well, though
The short version of this is Etali, doing Etali things
Consider that Murderous Cut cannot prevent a creature like Siege Rhino from triggering its ability when it enters the battlefield, it cannot kill a Planeswalker, and it cannot stop an instant or sorcery
But given the nature of the card, dead late, terrifying early, it's a no-brainer that 3 would still be the preferred number if legal
I purchased a few years ago from the 2002 Bakaboom one the 67/67 was denied which was kind of heartbreaking but I have a few more in que so maybe they grade the others
If theres a specific card that you want to add to your deck, you can usually buy it from online markets or gaming stores