I reviewed the spell, I was incorrect in assuming no portal was opened with a teleportation circle. In that case it should work out.

Glad you got a good group. My only real advice is stay consistent

Do you have a teleportation circle or a portal? A teleportation circle is like a star trek teleporter your velocity is matched with the destination on arrival no cannon.

If you have horizontal portal then sure you could drop a Boulder down such a shaft but I would be careful as this is open to exploit.