the prohibition spell description states:
You create a protection against magical travels that protects up to 40,000 square feet of floor space at a height of 30 feet above the ground. For the duration, creatures can not teleport to the area or use portals […] enter the area. The spell also protects the area from planar movement and thus prevents creatures from accessing it through the astral, ethereal, Feywild, Shadowfell, or change of plane to spell.
In addition, the spell damages the creature types you choose when you cast it. Choose one or more of the following choices: celestial, elemental, fecund, demon, and undead. When a chosen creature enters the area of the spell or begins its turn, the creature suffers 5d10 radiant or necrotic damage (your choice when you cast that spell).
When you cast this spell, you can designate a password. A creature that pronounces the password on entering does not suffer any damage with the spell.
The area of the spell can not overlap prohibition to spell. If you cast this spell every day for 30 days at the same place, the spell lasts until it dissolves, and the hardware components are consumed in the last cast.
Can you throw the conjure elementary spell to summon an elemental in the area of effect of the prohibition to spell?