Stickers are one of two major mechanics for Unfinity (the other being attractions, which we have not heard much of yet), and will allow you to modify everything from the name, abilities, and power-and-toughness of a card, right through to more esoteric things like its art and whether the characters in them are wearing hats
There are several reasons for this, which make the cards identifiable in a regular TCG deck
And that's why you haven't been able to play with Thought Vessel in Pauper for the past 3 and a half years - because they didn't want someone to feel bad opening a Common in a 2015 promotion that ran for 3 weeks
You can view your cards on the collection page
That said, I was able to survive long enough to achieve this and if I can do it, most players will be in the same boat
Matte reduces glare so the image is more readable in bright light