A little something extra achievement in Dungeons 3

You get the bonus creatures for sacrificing heroes from your prison to the hell-hole.
You need these for the achievement:

sacrifice 5 rogues/thieves - get bonus arachnid
sacrifice 5 wardens - get bonus imps
sacrifice 5 priestess/novices - get bonus succubus

You also get a reward for sacrificing 5 snots and for 5 gobbers but those aren't needed for the achievement.