The Deck of Psionic Powers
was a supplement for AD&D2E, it had 288 cards with all the powers from The Complete Psionics Handbook
, The Will and the Way
, and Dragon Kings
. I've had it for a long time, don't even have the original box anymore, but I kept the cards. The price is going by roughly what it sells for on Amazon.
The cards are about index card sized, just as wide but not as tall. Most powers could have gone on a smaller card, but a few required the space for the full description of the power. As far as power descriptions goes it's great. As far as the overview, not so much. It does have the information there, but all the cards look almost exactly the same, with purple ink and a design. Sciences are differentiated with open eyes, devotions with closed eyes, and each discipline has a different icon. I would have preferred something more noticeable though, or some colour coding. The psionic battle cards were also really bad - they would have on the front "Psionic Battle Card" written, with both "Attack and Defense", you wouldn't know which it is until flipping it over and reading the description. This is the reason I'm giving it a style of 2. While everything is clear and easy to read, and there's nothing really obvious, it's a poor design choice. Also, going through 288 cards, which can end up out of order, makes a specific card hard to find. With a book you can flip to the index, find the page, and go to the page. The cards of course have the advantage that the player can keep their psionicist's powers with the character sheet and not have to flip, but that's what they're designed to do, so they don't get bonus points for it. The psionic battle card design choice was just awful. Definitely the 4E power cards choice of using colours helps a lot.
For substance, they're great. It's every power (that I'm aware of) for 2nd Edition Psionics in one box. It doesn't take up much space, and it's particularly useful if you're not adventuring in Dark Sun making The Will and the Way and Dragon Kings uselsess for you otherwise. I also like that they don't use the screwed up Player's Option: Skills and Powers Psionics rules. The descriptions are full, so there's no need to reference any book for a more complete description of the power. The Complete Psionics Handbook and the Deck of Psionic Powers is all you need (or alternatively, the Psionics rules in the Dark Sun Boxed Set).
In play, the benefit was twofold. For character creation it speeds things up, there's no flipping back and forth to choose powers. You choose a discipline, grab all the cards from that discipline, select the ones you want, put away the ones you don't. Then compare them all right in front of you, with no flipping until you work down to the 3 devotions and 1 science. It speeds things up a lot, and also saves you having to write them down. During actual play, the benefit is in being able to look the powers up quickly, you don't even need the book on hand, so it's maybe 30 seconds that play stops for, rather than 2 minutes.
These benefits definitely show the advantage of having power cards - be they for psionic powers or wizard and priest spells. Even if you don't have purchased cards, writing the powers/spells you have down on index cards helps (although that can be time consuming itself). So based on that, I'd assume the Deck of Priest Spells and Deck of Wizard Spells would be equally useful. I'd also figure any such card accessory would be useful. As far as Psionics specifically goes, it's certainly easier than writing everything out by hand, so if you're playing 2nd Edition with Psionics, and you can get your hands on them for a decent price (IE, less than what they're going for on Amazon), I'd say it's worth it buying them.