CGAUP = Custom Game's Acceptable Use Policy
EULA = End User License Agreement.
I don't know what the Hive's internal policy says, but exercising a copyright right that you are not authorized to use (ie. public display, distribute) is copyright infringement.
You can reproduce (copy), adapt (modify), distribute (sell, donate, or rent copies to other people) and public display all those copyrighted you mentioned assets only if you have the respective license/authorization to do so. Licenses will often restrict those rigts (ie. non-commercial distribution; non-commercial display). If you don't you are messing with the owners.
Also, in the CGAUP you WARRANTED the following:
"You represent and warrant that neither the content you use to create any Custom Games or upload to the Service, nor the compilation, arrangement or display of such content (collectively, the “User Content”), infringes or will infringe any copyright, trademark, patent, trade secret or other intellectual property right of any third party".
I would bet that this is also the Hive's policy.
This is a good old handwashing. What this means, is that you are infringing copyrights in your modding activity you are ALSO breaching the CGAUP (contract), which also incorporates the EULA. The EULA has indemnity clauses (if Blizzard suffers, is you suffering in fact). The inclusion of copyrighted material on a map, plus the use of it in any copyrighted right form (in our case the rights would be principally distribution and public display), could be detrimental to Blizzard (the copyright owners will most likely blame them, also Blizzard thinks the custom games are their property), which can in turn, as you violate the warranty, make you paying them the expenses and other damages.
If you are going to use copyrighted material, try to use Blizzard's assets as both interests (yours and theirs) converge. You can also use public domain assets, which you can also freely modify or use as base.
