I'm trying to find out how I get this leatherworking recipe?
Knightbane Carapace

Anyone know how to get it and where?

Thanks
WIndsaber

According to WoWhead, it's dropped by Lord Jaraxxus, The Beasts of Northrend, and The Val'kyr Twins in ToC... I'm assuming 25 man, based on the ilvl. It MAY drop in 10 man on heroic.

it's hot though :)

Yea its from 25 man and 10 man heroic. If you plan on making it you may want to wait till the orbs for 15-20 triumph badges next patch update.