At some point in development of JA, there was to be an NPC known as the Cultist Destroyer. It would instantly go into a rage mode and try to suicide bomb next to the player. While I haven't talked to Raven about why this NPC was removed, I can only speculate that it had something to do with cultural reasons (suicide bombing was oft-reported in the news during 2003's Iraq War)
However, the .npc file and code is still intact, meaning this NPC was cut very late into development. There is also a cultist_commando npc which never appeared, and fully works (it has dual wielding blasters! awesome!)
Anyway, enough talk. You can spawn this NPC using an npc_spawner entity with npc_type "cultist_destroyer". The NPC will go into a rage, disappear and you will die instantaneously. But there's no effect? Easy fix. The effects for the NPC didn't ship with the game but we can add them back in.
For this you'll want to create a new PK3. In this, add an effects folder. Inside of that, a folder called force. Inside of this folder you will need an EFX named destruction_exp.efx. If you have no experience in creating an EFX file, that's okay, you can reuse an existing EFX like the rocket launcher explosion effect or one of the env/explosion ones.
I don't know the splash radius on their explosion as it isn't explicitly stated in the code. Your mileage may vary.