[zarlor]

Depends on what you mean by "custom" creatures. You should be able to create most things as portfolios, just make sure you select "Creature" as opposed to PC or NPC on the Character Configuration setting. Now if you're trying to build custom Monstrous Abilities that are not otherwise available then you may need to use the Editor to create those, although once you've created them you should be able to use them on the portfolio as normal (assuming you've set a source for that thing and selected your source on the Character Configuration screen.)

Now sharing your portfolios and encounters... well, if you did custom Abilities you'd need to include the .user file you created with that using the HL Export utility, which also has the ability to select a directory and file of portfolios to include. Not sure if "encounters" can be included that way, though. At any rate that's how you create a .hl file... which now that I think about it is actually what I meant to say above that a .stock file may just be a .hl file (instead of a .user file as I said above.) That's strictly conjecture on my part, though, I'd have to play around more to figure out any of that part, really.