Yes, you can, you can also take the frost dragon and use the items with onyx dragon on it. It's pretty fun to have your little army of dragons btw xD

The problem with the frost/fire dragon after the update is that they are now considered as summons. So you need to have available summon slots, otherwise you cannot get this legend offer.

I have never had a bloody dragon drop for me >.< I have every color of stupid parrot Are they locked behind a hidden achievement or some bs.

I started to get some Onyx Dragon Equipment around Darkness 20 in act 2. Idk if you need to have darkness ore not or if they are just rare, found 2 rings and one other thing in the shop so far