Rise of the Argonauts

This achievement is quite simple and you should be able to get it during a single playthrough without issue. See Whistling Wolf's helpful hints and the guide he linked to under "Corona, Crown of Mastery", but here's a few tips to make sure you don't miss this:

This constellation consists of killing blacktongue minions and blacktongue bosses. Most bosses are non-missable except for one important exception. When in Tartarus, you will run into the traitorous Nessus near the end of the level. You MUST kill him to complete this constellation. The option is there to spare him, and if you do one of the feats of the constellation will not kick in, thereby making you miss this.

The second tip is simple, you will probably have only killed 6 or seven (maybe less) regular blacktongue enemies when you land to reclaim Ioclus. Not to worry, there are tons of blacktongues here both on your way up to the palace and inside. The inivisible creatures protecting the spawn points inside the palace ARE blacktongues and count towards your total. You should get your 12 required kills easily, but to make sure simply run in past your fellow argonauts and take out the blacktongues early. This will stop tartarus fiends from spawning so ensure you have enough of those kills for the River Styx constellation before killing the final blacktongues.

And most of all, good luck!