Whatever you do, do not salvage your Diablo 4 Annihilus
The incredibly rare Unique Seal follows the same salvage rules as ordinary Seals.
Diablo 4 players have finally started getting their hands on the incredibly rare 
Annihilus Seal, and naturally, someone had to find out what happens when you throw one into the salvage pile. Sadly, the answer is surprisingly boring...
Salvaging an Annihilus gives you exactly 100 
Infused Horadric Resin. So do not bother, really, it is not magically going to reward you with a huge pile of resin.
Annihilus Follows the Normal Salvage Rules
Unique items like this often tend to reward either something special, or at least a little bit more salvage materials, but it seems like this does not apply to Annihilus. The result makes a little more sense once you look at how Horadric Seals and Charms are salvaged. The amount of Infused Horadric Resin you receive is based on the item's rarity, with the highest-rarity items giving 100 Resin. Since Annihilus is classified as a Unique Horadric Seal, it simply uses that same maximum salvage value. There is no special material, bonus currency, or hidden reward for sacrificing one of the rarest items in Season 15.
And it is probably something you will want to know before you test it yourself. Rob was the one who tested it for you, so thanks to him for sacrificing one for nothing!
Rob2628@rob2628𝕏Salvaging the brand new Annihilus Seal in #DiabloIV gives you this... F
Annihilus can drop from the extremely rare Uber Diablo encounter that can appear after World Bosses, so getting another copy is considerably harder than 100 Infused Horadric Resin. The Seal itself can also have valuable stats such as All Stats, All Resistances, All Skills, and Bonus Experience, and its Set Bonus can vary between copies. So unless you have somehow managed to get a completely useless Annihilus and genuinely do not want it, there is really no reason to salvage one.