The list will be in no particular order
Luckily for the Duskmourn: House of Horror design team, new doesnt always have to mean reinventing the wheel
The back of these cards looks especially dark and can easily be identified as such
Graveyard Recursion Phoenixes with self-recursion : 21 cards Syrix, Carrier of the Flame, Rekindling Phoenix, Skyfire Phoenix, Flamewake Phoenix, Lightning Phoenix, Phoenix Chick, Nemesis Phoenix , Everquill Phoenix (can also recur any Phoenix), Phoenix of Ash, Ashcloud Phoenix, Firewing Phoenix, Flame-Wreathed Phoenix, Skarrgan Firebird, Shard Phoenix, Akoum Firebird, Detectives Phoenix, Lamplight Phoenix, Sunstreak Phoenix, Kuldotha Phoenix, Bloodfeather Phoenix, Chandras Phoenix Most of our Phoenixes, can recur themselves, so we have a strong graveyard recursion strategy in our Phoenix Tribal
As long as its equipped, you can cast creature spells from the top of your library, and the boost it gives (+2/+2, vigilance, and green mana generation) makes any creature a threat and a ramp engine