There’s not a lot secret about this list. It’s 5 drops and can cover an incredible distance turn 1 if necessary with the Blood Reavers acting as a really solid second wave.
High model count is also great for objective grabbing and with immunity to battleshock from the portal of skulls they are really hard to shift.
Blood Tithe for bringing in those extra units is great but I feel the additional movement they offer is just as important.
Artefacts, Command Traits & Abilities
The Doppelgänger Cloak is great for the Wrath of Khorne Bloodthirster as it helps him stay alive whilst the horde units do their thing and mean that he will still be giving the bloodletters their re-roll 1s to hit when they attack.
The brazen rune is just a stellar artefact to guarantee stopping that one important spell that your opponent’s Army may be built around.
Wrathmongers are an amazing deterrent for those opposing big gribblies.
Gore Pilgrims getting that portal of skills up to range 36” particularly against that opposing magic and the re-roll to prayers is just massive.
Magic, Endless & Realm Spells
Pull unite off objectives or out of buff ranges or simply have a possible 3D6 mortal wounds combined from the Slaughterpriests.
It hits stuff hard every turn. It isn’t subtle.