These beasties come on a thick base, but can easily be removed from that base. I used a pocket knife to cut under the base of the model, separating it from the base. I then found a suitable flat base and glued the models to these. Once dry, I sanded the bases, but I have yet to flock them.
I can't remember which models are which, but the ones below I believe are a Star Vampire (left) and a Shoggoth (right).
I have been fortunate enough to get a number of Harpy Units on eBay over the years also. Saved me a lot of painting and there are some excellent paint jobs done by those I bought them from. You can see these units below.
Here is a close-up of the four nasties in question, affectionately dubbed (from left to right) as Snotty, Slimy, Shouty and Trevor.
In the game, their stats will likely be Chaos Spawn for Snotty, Slimy and Shouty, whilst Trevor will probably use the Giant stats or some house-rule stats for the Jabberslythe.
These mini's are a pretty good fit for Chaos style nasties and add some variety to the monsters available to the Beastmen.
