I didn’t realise that you were having some trouble finding them, so apologies for my rashness earlier. I took a look around and I found one response that was particularly enlightening. I’ll link it at the bottom. There’s also this information I took from another website.
Abaddon is also known as Apollyon
Rank: Prince of War
Abaddon is an advisor. He is Lord of the Abyss and King of the Demons.
“He is quite large, I would say at least 8 ft tall. He is stocky, wears a type of battle garb when I see him. He is dark looking with a dark complexion, eyes, and hair, along with a moustache.”
Credit to JoS.
While I personally haven’t evoked or made contact with Abaddon, he seems to be easy to talk to, so it shouldn’t hurt to ask these questions yourself.
Good luck in your future endeavours