Thanks for the comments, everyone.
Farlsy: No stack, no memorising, no gaffs. My preferred method would require an
extremely minimal set up (it would take you 2 seconds to pre-prepare) but the handling can also be altered very slightly to enable a totally impromptu performance. If someone jumped out of a bush and threw a normal deck, a normal envelope and a normal piece of paper at you, you could do this.
There's also no disappointing secret, either. I've noticed with a lot of marketed effects the description is rather different to what happens. I guarantee that the description I gave is exactly what happens.
Any two cards of your choosing can be predicted - I just said Two of Hearts and Jack of Diamonds purely because they were the first two cards I thought of as I wrote the effect up. Iain is correct, too - you don't need a deck of playing cards. You could do it with ESP cards, business cards or even blank faced cards with words written on the faces if you wanted to go down that road.
So there ya go!
Oh, and when I said a cross between Bill Malone and Derren I meant real old-school, knock-out card magic but with a hint of mentalism and psychology and finesse.
B0bbY_CaT wrote:could you do it twice? First time around you are predicting one card only, the envelope is in your pocket. Written on the envelope is "1st prediction".
Then allow the "know it alls" a moment to gloat (you could even add "it's not like I've got 52 pockets" or "I used to do this trick with 52 pockets but I could never remember which card I hid in which pocket") before putting a second envelope on the table, this time in advance. This envelope has "2nd Prediction" written on it. This envelope can be held by another spec, or left to sit on the table while you do the trick you describe above.
You could adapt it to do whatever you wanted, I suppose. Once you understand the method and handling, though, I think it'll be a lot clearer why plots similar to the description I gave would work best. The thing that hopefully blows people away is the knowledge that they chose both cards themselves, first by giving a random number and then secondly, more impossibly still, by just jamming the first selection into the spread deck at a random point of their choosing.
Mage Tyler wrote:I tip my hat to you for the ambition and creativity that creating new effects requires (and Iain for the assistance).
I must say it's refreshing to see someone willing to do some work and put themselves on the line for the (magic) world to see without mentioning a $25 price tag at the same time.
Thanks, Mage

Iain is definitely a big help to me. When I came up with the basic skeleton for how to acheive this, he helped me brainstorm ways to frame it as a complete effect. I (we?) finally settled on the idea of a sealed envelope containing two predictions. I think that plays best.
As for not mentioning a price tag... I have a fairly good idea of what I might do once I've fully completed this. I'll probably make it available free to members of this forum who have been around for more than a few months. Hopefully if people like it, it will help my reputation if I ever decide I'd like to sell any future effects.
Of course, I could just be a complete idiot and this trick might totally suck, haha! Iain seems to think not, though, which is a good endorsement as far as I'm concerned!