Tip[]
Supreme Slayer
Do not try to accomplish it on purpose, it'll be totally a waste of time! We know that the Easy Hardcore achievement can't be unlocked even if you've achieved the Very Hard Hardcore achievement, which means you must beat the game at least 4 times to unlock all hardcore achievements. As you're playing, you'll know that some achievements make you to create a lot of new characters, so my suggestion for Supreme Slayer is that choose the little boy(you know whom I'm talking about) and "levelup" him to 100 then upgrade the Ember Sentry skill in Battle series. Switch it on all the time and you'll kill tons of monsters even if you don't mean to attack them.