Oh, wow, these plans could really change fast. You'll need to promise everyone that nothing will change in your schedule, non unexpected event could change the way you develop the game. Will you be able to promise that when many things could still change, be removed, replaced or added?
Hmm. I think how many spells, traps etc. will it be in the game is hmm... very difficult to tell right now - I mean we need to know everything about game mechanics. Let's think about i.e. a new trap, well... but why we need this trap in the first place? What is so dangerous we would need to set this trap against at?
I think we'll get the answer when we finally know how many types of threats Dwelvers will offer to player - types of damages, types of armor, strengthens and weaknesses, types of personality that could react to our new trap - knowing that how many of threats we can experience in Dwelvers it will be much easier to tell what threats we missed that should be repelled somehow.
I.e. there are some powerful range skills that are very destructive - what if there would be a trap that could consume such powers and use against caster or even more enemies in range? Should it friendly-fire our creatures too or not? Etc. Knowing ALL mechanics first it will be super easy for community to make ideas perfectly matched for their needs - if game doesn't have that than people makes mods right? Well, let's make that possible of course, but better not let that mod be much better than original content IMO because game image become a little beaten up (like Fallout 4 mod that enable player to see what your character will actually say after choosing certain answer during conversation - normally games only shows short possible answers that can really sounds different and you can react to this like - wait, what? I honestly didn't want to say that like this, OMG! <consternation>).
I just think it's always easier to make a solution for a problem than to make something from nowhere just to add more content - it need to be perfectly balanced with everything other.
Example? As always my favorite - Pokémon games - they've set every types of elements and moves than they made their counterparts, defensive moves against attacking moves or buffs and debuffs. Making specific creatures that has these stats and that moves was than so simple now they made them 721! And it's still quite balanced.
So what I suggest is to make lists of these all mechanics, put on the whiteboard and than make everything in some sort of rock-paper-scizor game as well as what we can produce, how and from what and than assign specific types of creatures to run them - but not give one concept for such creature but few and let our community decide which can be the best!