A Spirit Troll is a troll that was nearly killed with psychic energy and has regenerated as a nearly incorporeal creature whose claws and bite are actually psychic damage. It's a hefty "Challenge 11" monster that will wreck a low level party. Frankly, I'm not likely to get a huge amount of use out of it, but I thought it was such a unique critter that I might as well pick one up while it was for sale as I wasn't going to find a great model for it later.
Black Pudding. Great monster, awful name. It's a tar coloured ooze that splits into new ones when its taken more damage. Which I should sort out miniatures for, as I hadn't noticed that when I ordered it. Bother.
This mini is nicely set up so you can set someone up to be devoured by it. Here's a poor modron getting eaten by an ooze. It's got strong "Marvin" vibes to me. "Oh no. I am being consumed. What an inconvenience."
And the last big but not very good monster is this giant Dragonfly. It feels like a good thing for weird or fae encounters at low levels. The shimmery, iridescent wings look great in see through plastic and would have been super hard to paint.
All in all, a good set of purchases, I reckon.