If you would do a textarea with a convention, I for one would like it somehow like one of these:
a) hardcode the order of the parameters according to relevance and leave empty the fields that don't concern you:
Lightning Bolt|3|Magic 2010|foil|promo|mint|english
Mimic Vat|4
Unsummon|4|Magic 2010||promo
or
b) same as above, but grouped by edition
Magic 2010
Lightning Bolt|3|foil
Unsummon|4||promo
Scars of mirrodin
Mimic Vat|4
But to be honest, I think a more simple and elegant solution is a data grid and the option to choose the columns that concern you.
Whatever the method, the biggest problem is that such a feature would really benefit from an autocomplete dropdown, seeing as whatever method you choose, there will be a lot of typing involved. Really looking forward to this though, in any form.