Never heard of em till now.
In the context of where the term comes from, the Deavas or Divs are the “demons” of the Zoroastrian faith. The other term is Deva which denotes the vedic gods. Where the demonized Deava comes from.
They are demonized vedic gods in simplest terms and the main spirits worked with in Black magic of
Are they safe to work with?
Depends on your definitions of safe?
Is practicing magick in general safe?
As with any current and works in magick there are risks. But also a large potential for growth.
Are the devas them selves hostile?
The thing to remember is the Deavas are the demonized devas or vedic gods.
Working with the devas or divs is to a work with a god that has all precepts of imposed humanity stripped away.
An example of this is Sovar leader of the Deavas is the demonized form of Shiva.
Another example is the connections between andar the demon of apostasy and rebellion, indra the vedic thunder god and thor.
Can they be hostile, yes about as hostile as any other god one may work with.
Daeva may also apply to the god forms of Hinduism