How do you know which cards opponents are holding in their hand?

Replays are able to identify cards if they're shown later in game after being played.

Written by Benedict
Updated over a week ago

Once a card is played from hand we can deduce when that card was drawn, discovered, or created in any other way.

We're also able to identify cards that an opponent did not kept during the Mulligan if they draw and play that card later in the game: