You really don't need three spell sets for raiding as a 2021 necro. With the dot revamp, you'll probably cast 11 dots counting your wounds. But the time you lay down the 11th dot, you'll be wanting to refresh Klraggek, Venom, and Oblivion. In fact with dot slots being the way they are, if you're raiding with multiple necros, you'll want to be sure not to case any relatively low dps dots. On the right raid mob, you can put out insane dps without changing spell sets. On the Zlandicar raid for instance (a great EPeen Deeps raid), our necros can do 1.7 to 1.9 million dps without swapping spell sets. If you look at the thread, this was created in 2018 when yeah, fuck playing a necro, you had to lay down so many GD dots.