Copy-paste Death and Decay macros for Death Knight in WoW Midnight: self-cast and cursor versions, ready to use. Add Shift/Ctrl/Alt spells, raid markers and a chat callout in the macro builder.
Open the macro window (/macro), make a new macro and paste: #showtooltip /cast [@player] Death and Decay
Open the macro window (/macro), make a new macro and paste: #showtooltip /cast [@cursor] Death and Decay