The rare great cobras live in damp places and are sometimes encountered in groups. They cannot be surprised with a sneak attack and their own aim is deadly. They are also immune to poison, fear, and mind affecting spells.
Spitting cobras have a nasty ability to spit their venom feets away, aiming at the eyes of their prey. There's no chance of sneaking an attack on these quick creatures, nor are they susceptible to mind affecting spells or fear. Unsurprisingly, they are immune to poison as well.