A deck is not shuffled if the judge believes a player could know the position or distribution of one or more cards in his or her deck.

Generally, when searching a deck, a player will at most notice the position of a few cards. By doing one or two rifle shuffles, that player will no longer know the position or distribution of the cards in the deck, which means that the deck has been shuffled thoroughly.

However, if all counterspells are known to be stacked together, then after one or two rifle shuffles, they'll still be relatively close to each other, which means the same method of shuffling is no longer sufficient.

Because Alex stacked the cards, Niobe will have to shuffle significantly longer. Even though his actions may be legal, strictly speaking, it feels like he's getting close to the definition of slow play to me.

Besides, am I correct when I say that it could be cheating if Alex then saw Niobe give one or two rifle shuffles (which he should know to be insufficient shuffling as he stacked the deck) and doesn't call attention to it?

Originally posted by Michel Degenhardt:

it feels like he's getting close to the definition of slow play to me

That feels like you're looking too hard for something, anything that might be “wrong”.

I believe the answer to your question is already covered in this thread.

d:^D