I got the same offer!
So you get the points that are redeemable plus EQP is what I'm assuming based on your comment?
Also, if I have the IHG card, do I have to use it for the 20% discount? Or can I still get the 20% discount if I use a different card to pay?
Yes, the EQP you buy are also added to your redeemable points balance. I used a different card and got the same $640 price.