Discover offers $50 and $100 Airbnb gift cards
for redeeming the Cashback Bonus
. No quantity limit that I know of.
$50 Airbnb gift card for $45 Discover Cashback Bonus (eCertificate or physical card).
Log into your discover account - go to Rewards - Redeem Cashback Bonus - Gift Cards - Airbnb
If you choose to get the physical card, shipping is free as well. Usually arrives within a week or so.