Its normal that every manga chapter has some cliffhanger (maybe except when an arc ends), but I like how it is on this one. Its not so extreme that they butcher the story just to make a cliffhanger.
Magic is NOTHING compared to modern technology. They can inflict as much or even more damage than magic itself. From firearms to WMDs, magic pales in comparison against what humanity made over hundereds of years
Yknow instead of summoning a giant rock earlier, why not summon uranium from the earth God and use the fire God to detonate it with thr required force for nuclear fission aka nuclear weapon.
Depleted uranium bullets would've also made a nice touch on that slug-round based gun. That and flechette design rounds for taking out the eyes.