Use of Dota 2 game assets for Non-commercial purposes

Can you use Dota 2 game assets for non-commercial purposes? YES!

In a thread in dev.dota2.com titled "Android app removed due to IP infringement" by Voshond, a Valve developer named Liam replied with the following:

This is Liam at Valve. I'll reach out to Seifer and Voshond directly, but here's how we generally address use of our intellectual property by customers: 

Under the Steam Subscriber Agreement, we allow our customers to use game assets (art, etc.) for noncommercial purposes in support of the game community. For example, we're happy to see free mods of our games. For apps, that means free apps are ok. We don't allow customers to use our assets in paid apps (including apps supported by ingame sales). 

If apps refer to our trademarks, we permit people to refer to our trademark to indicate compatibility or a reason like that (e.g. "XYZ Companion App for Dota 2"). We don't (and can't) allow customers to use Valve trademarks in a way that suggests their apps come from Valve (e.g. "The Dota 2 App!"). 

In addition, use of the web API is governed by terms posted here: http://steamcommunity.com/dev.

Link to Liam's reply: http://dev.dota2.com/showthread.php?t=133219&page=3&p=1140729&viewfull=1#post1140729

If you check Section 2.D. of the Steam Subscriber Agreement, it states the following:

2. LICENSES

D. License to Use Valve Game IP in Fan Art.

Valve appreciates the community of Subscribers that creates fan art, fan fiction, and audio-visual works that reference Valve games ("Fan Art"). You may incorporate content from Valve games into your Fan Art. Except as otherwise set forth in this Section or in any Subscription Terms, you may use, reproduce, publish, perform, display and distribute Fan Art that incorporates content from Valve games however you wish, but solely on a non-commercial basis.

If you incorporate any third-party content in any Fan Art, you must be sure to obtain all necessary rights from the owner of that content.

Commercial use of some Valve game content is permitted via features such as Steam Workshop or a Steam Subscription Marketplace. Terms applicable to that use are set forth in Section 3.D. and 6.B. below and in any Subscription Terms provided for those features.

To view the Valve video policy containing additional terms covering the use of audio-visual works incorporating Valve IP or created with The Source® Filmmaker Software, please click here: http://www.valvesoftware.com/videopolicy.html

If you get a "Violation of the intellectual property and impersonation or deceptive behavior provisions of the Content Policy" from Google for your Android app, it may be because your app name starts with Dota. Examples of this are "Dota 2 Quiz", "Dota 2 Assistant", "DotA 2 PEDIA", "Dota 2 Wallpapers", "Dota 2 Guide", "DotA 2 Database", "Dota 2 Art", or "Dota 2 Builds". Although not guaranteed, it is safer to have an app name that follows the format "X for Dota" or "Y for Dota 2". So from the examples, it would be "Quiz for Dota 2", "Assistant for Dota 2", "PEDIA for DotA 2", "Wallpapers for Dota 2", "Guide for Dota 2", "Database for DotA 2", "Art for Dota 2", or "Builds for Dota 2". But, if you are going to have the word "Dota", "DOTA", or "Defense of the Ancients" in your app name, I suggest that you follow Valve's Dota Trademark guidelines found at http://www.valvesoftware.com/trademarkguidelines.html