Have you tried your wad on DsDoom with and without the MBF, just to confirm if the reason why it crashes is because of the MBF dog? Have you tried another custom wad with MBF support on DsDoom, just to make sure if it really supports MBF? Depending of the results of those tests, maybe you can try adapting the MBF dog in your wad, in order to make it work on DsDoom.
Regardless of the tests above, my bet is that DsDoom has no MBF support, or at least not a full MBF support. That being the case, then you could try some of the solutions below:
- Report the bug on this topic
, to see if you can get help for the developers of this homebrew (they haven't released DsDoom source code, so only they can fix it);
- Recreating the MBF dog without MBF (probably using DeHacked to change the behaviour of an existing monster in order to make it behave similarly to the dog);
- If you have a 3DS, migrate to PrBoom3DS
. I have it on my 3DS and I find it simpler to use, with more customizing options (probably they based on a PrBoom version with a better MBF support).