@Green Yeah, this is what I was picturing:
*Terrorist gets hammerspace power
*Terrorist stuffs it to the brim with knives and road spikes and ball bearings and the like
*Terrorist encases himself in something air-tight, like maybe dumping cement over a steel box.
*Terrorist kills himself, prompting the hammerspace to try and force all of the things he stuffed in his hammerspace into the tiny air-tight cement prison.
*The stuff has to leave the hammerspace, so it eventually applies enough pressure to make the cemented box explode massively.