This synthetic explosion sound is bigger than that of "ExplosionBombBlastAmbient", giving a hint of a large fireball that rises for a few seconds after the initiation of the blast. Still, it is totally synthetic (not a recording). Pretty good, I think. Created in Cool Edit Pro.
@FD_Bratish, however, I would be happy to just grant you a license to include my sound in your derivative work, and then of course you can do whatever you want with that derivative work. I will even grant that FreeDoom can use it. You can even do all that without attribution, if there is some particular reason you can't provide attribution. I will even hereby affirm that I give you permission to include it in this work of yours with the understanding that said work is to be redistributed under the BSD license used with FreeDoom or a patch for it, or whatever. But I'm not interested in putting my stuff into the public domain.