The corpse, a chicken leg bone wrapped in a leather strap, and a letter with the message written in the casters blood stuffed into the mouth of the corpse.
I played the same necromancer character for 12 years, twice a week for about six hours. (Doing math) 7488 hours give or take (Most likely give as we did a few Christmas holiday four and five day sleepover orgies of gaming) of playing good ole' Hexus.
Holy shit that's 312+ days.
Anyway I wrote hundreds of spells for him. All Necromancy/Alteration if you want any. They'd need some conversion because we were playing First Edition + Unearthed Arcana and Second edition but many of them are fucking pimp and none were rules rapey. (We played a really conservative campaign and retired our characters on or around level 24 after 12 years of playing.)
Many of them are high level, but hey, that's what villains are for, right? Springing spells no one has seen before.
Example spell -
Hexus's Improved Wall of Boney Bones
Necromancy/Conjuration
Components: V,S,M
Duration: Special
Casting Time: 1 round
Level: 8
Creates a wall of bone that erupts from any open, natural surface (Earth, sand, stone, etc) Volume created is 10x10x2 feet per level of the caster and can be configured in any shape the caster wishes, (Square, hollow cube, dome, stairs, you name it so long as the volume is sorta correct.) The wall is a permanent construct and each 10x10x2 segment can withstand 60 hit points of damage before collapsing.
On the round after casting, for every 10x10x2 segment of wall created, one six hit die skeleton will step out of the solidified assembly of bones in service of the caster. They will follow verbal commands with up to five simple variables at a time. (Example - "Climb that ladder, enter the door up there, kill anyone in the room, pick up any books you see, then return to me.) The Skeletons speak and have comedic personalities in strict accordance to the rule of funny. They move quickly enough to roll initiative rather than to automatically act last in the round like other skeletons. They are otherwise identical to a standard animated skeleton and will continue to serve their master until destroyed. They carry femur bones that act as a club, doing 1d6 damage.
Note - These skeletons make a lot of racket and constantly make puns about bones, sex, and sex with bones. They are not conducive to the achievement of stealth. They also each refer to each other by a unique name.
Material components are a vial of the caster's blood, a ruby worth 1000gp, any bone from the hand of a cleric or priest, and the seed or nut of a tree.
Hexus's Improved Wall of Boney Bones can be used in combination with Hexus's Bones of Steel to create sturdier permanent structures and buildings.