I got this email from discover, Iv'e never kept a balance on my cc, wondering what effect it will have on my cs if I utilize 50%+ of my available credit on this card and pay only minimum payments till the promo expires?


Credit score is calculate also based on your utilisation. So your score will drop I'd you u are using 50% of it.
However, if you don't have any plans for a mortgage/loan/lease or so , and you need that money. It's the cheapest option do do. Again it's depends your nedes.
Keep in mind that there's business card with 0%apr as well and they do not report, so it will be a better option to consider..