On the topic of colorless mechanics

One of the benefits of shuffling is that technically, you're not allowed to reorder your library when searching. But just like graveyard-order matters, that's a pain to keep track of, and even worse, the library is a private zone so your opponent can't make sure you don't cheat

Mmm. Even if you do have order preserved, this will slow down in any deck using it. Every tutor becomes "And now I know everything coming up. Should I shuffle it away? No, better write it down to keep track."

Shuffle it away? Why would you do that when you can ignore it!

Maybe this shouldn't be a may. You literally cannot shuffle.

Well, that's a little bit less useful. It still means you know what's coming up; but you cannot choose to say "Nope, hate that, I won't take my ignore option, and will shuffle".

Still costs all the time of note-taking though.

Probably safest to only prevent shuffling that's not accompanied by a search, but then it gets quite awkward.

How often do you shuffle without searching? I'd think that's the most common use case

"Target player shuffles their deck" is rarely a thing. I mean, there are decks that it would be a good counter for, but there are usually better ways to do it.

Yay! Soldier of Fortune for victory!

People actually used to use Soldier of Fortune when Vampiric Tutor and company were commonplace. I also heard that some jerks used him to force concessions when ante was around. Don't want to shuffle my Mox Jet too many times. That's going to ruin its value!

sigh. I am old.