Monster Crown (UP)

The legitimate way to get this is to find the secret island after saving the raptor's child and flying there. Once there there are 3 towers to find that contain secret bosses that increase in level and difficulty. Greed is in the centre one and Torture is in the left (presumably Worship is in the right hand one). Worships level is high - 100+ greed was level 75, torture was level 90. And tough with hard hitting attacks. I used a technique of infection status effect and rapid healing to chip away at their health.

However, I didn't need to fight Worship because the achievements are bugged and I got this one when I fought and beat Greed - and got the one for fighting greed at another random point. Got the one for beating Torture when I beat Greed. Basically it's a bit of a merry go round with the achievements as they're buggy and don't work the way they should. Good luck!