Nothing too complicated here. The artist used iubeo + an infinitive verb, although iubeo + ut + a subjunctive verb might have worked just as well. I’m translating interficere as passive rather than active because it fits English idiom better that way.
The angry king orders the priests to be killed, and Daniel overthrows Bel along with the temple.
Continuing Bel and the Dragon, this depicts Daniel 14:21. The priests get their comeuppance. I wonder if it was all worth a few free meals? I especially like the little boy voiding his bladder onto the head of the toppled idol. That’s a nice touch. The artist implies that only the priests were killed although the Biblical passage could be read to include the wives and children as well.