Love your optimism, keep that going :)
I would actually suggest against having a direct Riot connection during the process, organization and implementation would be better done on the fan side because it lacks the possibility of corporate influence as well as opens up an easier time with overall communication, organization and contributions. Riot has to worry about making a tool that works too well public, as even with their generous API if it's too good people will try to profit.
The biggest issue that I can see is the variability of the needs of conceptors. As Hyrum said, most baseline examples could be generated off of existing champion abilities, with recolors and the like.
Now another thing I want to point out. A lot of the things you want in a concept design, abilities, animations, modeling, textures and game interactions can actually be done with a single freeware program I know of. Blender. I've actually been messing around with it in my undergraduate research for 2 months now and it's a great program. However, it has a huge learning curve. So much so that I would consider anyone well versed in it as a specialist.