If you need barghests for your next adventure herein you will find a wealth of options and detail to make them a lot more than just the next monster for the party to beat up.
To remind you, a barghest is a shape-changing fiend that usually presents as a wolf or a goblin and which has the disturbing ability to increase in power if it eats whatever it kills. At the hardcore mechanical level this works somewhat differently depending on whether you are using the Pathfinder or the Dungeons & Dragons 3.5 ruleset, so if this detail is important for you both are dealt with in exquisite detail. As far as the party is concerned, it starts nasty and gets nastier... and when the dice hit the table, precise ruleset-based differences pale, you could actually use either to effect whichever set of rules you are using.
This is very user-friendly, particularly if you are reading the PDF onscreen rather than printed out. After the initial preamble that explains what a barghest is and how you might want to use its particular nature in an encounter (or even as the focus of a whole adventure) there's a set of lists (one for each ruleset) that gives a range of options ordered by CR. Click on the one of your choice and a hyperlink takes you to a full stat block. No messing with a generic stat block and notes telling you what has been changed, you get a full block for each and every option!
So once you have chosen the variant/CR you need, everything is to hand to enable that barghest to be dropped straight into the encounter that you have planned. Even if it survives and increases power during the course of the adventure, it will be straightforward to select the right set of stats for the next encounter - even during the course of the game if you keep your notes on a laptop or tablet! A nicely done GM aid.