No heavy armor for clerics though, only light and medium. Although the DMG has a Death Domain for the cleric class, which gives access to Necromancy Spells. This may not be a problem if you're rolling for stats, but array or point buy can become fairly limiting.Īnother potential solution could be a cleric, but I'm not familiar enough with the class, so I don't know what spells they can get. It's also a MAD concept (Multiple Ability score Dependent) as you'd want High STR and INT, with fairly decent CON. You could always get a feat for Heavy armor, but I'm not sure if it's better.
Maybe 1 level in Fighter or Paladin and then full Wizard Necromancer (not bladesinger as bladesong doesn't work when wearing medium or heavy armor). You can get necromancy spells and have pretty decent melee capabilities, although you'd be wearing light or no armor. If you want to create a character loosely based on Lich King. Definetely not raising an undead Ancient Dragon servant. I'm not sure if even a level 20 PC (per RAW) can do what you're asking for.
Talk to your DM and maybe he'll accept to change paladin spells for some necromantic ones. If it's for a PC to play with in a real game, I doubt you can make one without breaking several rules.