Nora Cost: 53
Hit Points: 46
Abyssal Fiend used to be 2x autoinclude. He has suffered MANY nerfs at the hands of the devs, including losing Flamestrike, cost increases, the Scorn nerf, Amplify nerf, and others. Around the time of Grimlic's Descent, it was very common to see two Abyssals deployed for 50% Amplify Fire with a Grimlic in the back smashing things for about 26-27 damage per hit.
The Fiend was a hated rune for a couple expansions, and unfortunately his current role is as a niche rune.
Recommended Builds: Amplify Fire/+2 DMG (Fire BG), otherwise +6 HP/+2 DMG
Abyssal Fiend is a highly specialized champ. He is basically only viable in two types of decks, Deep Elf/Treachery or a Fire Amp BG. The combination of Demon Elf Bound, Scorn and Vulnerability- Frost make him difficult to use in this age of smooth meta champs you can just slam down without being careful about how to approach using them.
His saving grace is his cost. 53 Nora is insanely cheap for anything with 6 SPD and 12-14 DMG, especially one with Multiattack. This makes him potentially a three-star champ if you can cover the Deep Elf requirement and make use of his Amplify. The obvious deck that springs to mind is Grimlic's Treachery; on the other hand, however, you could easily use that Nora for another Deep Elf. It's all up to you, but I would only use Abyssal Fiend in a deck centered around Grimlic's Treachery... Even a Fire Amp deck is iffy.