Eiame's Wall of Writhing Dragon Wyrms

You create a wall of writhing dragon wyrms on a solid surface within range. The wyrms attempt to stop trespassers through the use of grappling and biting. You can make the wall up to 100 feet long and 20 feet high, or a ringed wall that must be 15 feet in radius and up to 20 feet high. The wall is always 5 feet thick. The wall lightly obscures vision from either direction and lasts for the duration. It is traversable as difficult terrain.

When you cast the spell, you must specify which side of the wall you wish creatures to be kept on. There must be at least 10' of space available on that side of the wall.

You also must choose a damage type and a related dragon: acid (black, copper), cold (silver, white), fire (brass, gold, red), lightning (blue, bronze), or poison (green). The colour of the wyrms are of the dragon type selected. 

If the dragon type you choose matches your draconic ancestry, the wyrms will nor harm you, and you will have resistance to the wall's damage type from all spells and effects for the length of this spell.

When the wall first appears, each creature within its area is subject to Wall Damage and a Wyrm Grapple Attack. Each creature within 5 feet of the wall is subject to a Wyrm Bite attack. (See creature stats below for explanations.)

Thereafter, any creature venturing to within 5 feet of the side of the wall you specified is subject to one Wyrm Bite Attack for each 5-foot square adjacent to the wall they move into. Attempting to cross the wall from that side results in Wall Damage and a Wyrm Grapple Attack. Creatures approaching the wall from the non-specified side will be attacked with one Wyrm Grapple Attack when within 5 feet of the wall, and for every 5-foot square they move into adjacent to the wall, even if they got to that side by going through the wall. If a successful grapple moves a creature from one side of the wall to the other, the creature takes Wall Damage as well.

The wyrms' 5-foot reach also extends laterally from the end of the wall if there is space there. 

Wyrms, and thus the wall, can be attacked. When a wyrm is killed, a permanent 5-foot breach is made at that point in the wall, though the wyrms on either side are within attack range of anyone trying to move through it, so the wall's attack defenses still apply. However, creatures making it through a breach take no Wall Damage. Moving through the center of a 15 foot breach avoids all attacks.

Note: A creature trying to cross the wall from the specified side will have to endure a Wyrm Bite Attack at the 5-foot mark, Wall Damage and a Wyrm Grapple Attack when they enter the wall; another Wyrm Grapple Attack should they make it to the other side; and, if that last grapple is successful, one more Wall Damage as they are transferred back. 

 At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, each damage roll increases by 1d8 for each slot level above 6th.