Overlord stats predicting a villain's rise is honestly a bit overcomplicated in most of the web novels I've been reading lately. I see people fixating on Intelligence and Charisma because of characters like 'Overlord' Ainz Ooal Gown, but I think the real predictor is something less flashy: Logistics. No, seriously! If a villain's got insane Undead Summoning or Crafting skills, that's what builds a sustainable empire. You can be the smartest lich in the world, but without the passive mana regeneration to keep your skeleton army topped up or the Alchemy to equip your minions, you're just a fancy dungeon boss waiting for the heroes to rest and recharge.
That said, I've seen authors totally ignore this and just jack up the villain's Level and raw Attack Power, which makes for a boring, linear power climb. The memorable ones, the ones that feel like they earned their throne, always have a weird secondary stat maxed out—like Territory Absorption Rate or Minion Loyalty Threshold. Those are the stats that let a villain go from a local nuisance to a continental threat. I drop a series fast if the overlord's growth is just a numbers-go-up screen.