ShiKage's Infighter Build

I would say that a level 11 Energy Drain would be enough if you want to use it. It's not something you'd probably use often since you'd probably have to potion to survive any real damage taken after 8x. It'd be impractical to use Energy Drain every single time, and at level 11, it'd still heal 50.4% damage which is useful enough to save potions when you have the time. Level 20 only heals 72% damage. 22%, and you're not doing a significant amount more damage, unlike Energy Buster. With a range of 1000~2000, you'd heal, on average, 756HP with Level 11 1080 with Level 20. The damage difference is 675. The difference in Energy Buster is 810 damage per monster. It's like Chakra. Situations can call for it, but there's more useful things to do about with your time in most scenarios. Unlike an Assassin, Infighters cannot rely on some ungodly amount of Avoid and range to waste their time Draining without fear of being hit. Infighters have to practically stand on monsters 100% of the time, thus incurring touch damage very frequently. If you want to save on potions, the extra 22% damage isn't huge. You'll most likely be Draining a single stunned monster that you didn't manage to kill from a larger mob to finish it off anyways. It's not something you'd be using very often. Especially if you don't want to waste time or run the risk of dying because you depend on it to heal you.