can any arcane caster become a Lich? because if so, my players are going to have to deal with MC. Phylactery and his five man band.
It would take a few paragraphs to answer this one in-character without getting meta, but I don’t wanna do that, so an ooc meta answer is what you’re gonna get. Sorry.
Any caster, arcane or divine, can achieve lichood given mastery of necrotic magics. It also requires successful creation of a phylactery, a difficult process that is different for each individual. Though in more recent years (5e) liches are as-written more reserved to wizards, in my time (3.5) anyone with the Craft Wondrous Item feat who could get to Caster Level 11th (again, arcane or divine casting) and had 120,000 gp + 4,800 XP to spare could do it. Funnily enough, though the process itself is some serious necromancy, being a necromancer (or necroticly-focused at all) technically wasn’t even a requirement.
In any case, never let rules as-written tell you that your fun is wrong. If you want to game in a world where MC Hammer the Bard decided to turn to dubious magics in order to jam for all eternity, then you tell the rule books they can’t touch this.