Right now the cards enemies play show which item it comes from The problem is the cards spin by too fast to read if you have your animation at a decent speed If it is intended for people to know which items the enemy has then a "paper doll" should be added to the interface that opens up when you click on the enemy. Ideally the items which were "revealed" should be visible and the other items have the question mark icons. If it isn't intended that the item name be revealed then it should be removed from the cards.
If you want to view enemy cards you can just toggle "pause enemy cards" under options (defaults as "pause new cards") - it's entirely up to you if you want to take part of the information or not. I'd imagine seeing what items a card comes from can be valuable in mp - but it does take some item/game knowledge.
I would say this though - it would be nice if that information would retain after the initial playing of the card. right now, for some reason, if you view what was played in the battle log the item from which the card came from is no longer showing. I assume it's not intentional or else we wouldn't be shown that information in the first place when the card is played so a fix would be greatly appreciated. I can search for the item in the wiki myself if I want as I think alot of players do.
In my opinion, items should not be revealed top opponents in PvP games at all. Knowing what cards are in your opponent's deck may be useful information, and a lot of that information can be revealed pretty quickly if a player pays careful attention to which items are named on the cards that their enemy plays. So that serves as a motivation for players to pay attention to the items named on the cards. The problem is, doing that is tedious and slow. It involves memorising the cards of ever item, and then carefully inspecting every card that is played, and so on. I generally think it's a bad thing players can get an advantage by doing something really boring - because that essentially means that the game is encouraging players to do something boring... And I think tracking the item of one's opponent falls into this category. Thankfully it isn't really a big advantage to do this — otherwise I might feel like I actually have to use that technique, and I really would rather not. Revealing the entire deck right at the start of the game would reduce tedious task of trying to deduce the deck - but it would also be a bigger advantage and therefore more important to pay attention to. I don't think that would be an improvement. If the source item was still revealed when bring the card up by clicking on the battle log, that would be an improvement; because at least then it would be possible to just check whichever few cards you happen to be interested in without having to use the 'pause enemy cards' option. But I'd prefer it if the source item just wasn't listed at all for enemy cards.
Exactly same opinion as Karadoc. With added fear that someone will sooner or later makes program that automatically keeps track of opponents items and lists cards still in deck. No idea how hard it would be, but not impossible.
I agree that in the current PVP setup, knowing your opponents' items—while adding a layer of strategy some chess/poker/magic players may enjoy—would just slow down the game and give an advantage to players who care more about memorization, which probably isn't something that the devs care to do. That said, if we ever get a more mature PVP environment, with best of 3 matches or bracketed/swiss tournaments, it would be great if players had to register their builds (and sideboards, whether those be equipment swaps or a party member swap, that's another topic entirely haha). That kind of information, and the planning/strategy based on it, are clearly a healthy part of super high level play.