You create a wall of raging arcane power.

Select up to 16 contiguous 5 ft. x 5 ft. square spaces. A wall of hazardous arcane energy 30 ft. high forms in the chosen spaces.
(If multiple Arcane Walls occupy the same space, only the strongest wall has any effect on that space.)

The wall provides partial concealment, and is difficult terrain.
Any creatures in the spaces where the wall appears do not take damage from the wall until their turns.

When an attack tries to pass through the wall, it has disadvantage and you may roll a test of Spellcraft to block it if you roll higher than the attack’s roll to hit.

A creature which starts its turn in the wall
or ends its turn in the wall
takes 1d4 elemental damage,
+1d4 elemental damage per boost from Intensify,
and does not take damage from the wall again until the start of its next turn.

A creature which tries to move into a space occupied by the wall during its turn
takes 1d4 elemental damage,
+1d4 elemental damage per boost from Intensify,
does not take damage from the wall again until the start of its next turn,
and must try a contest of Strength against your Spellcraft.
If they win, they may move through the wall during this turn.
If they lose, they cannot move through the wall during this turn.

Deplete d4:
At the start of each of your turns,
if your Arcane Wall has damaged a creature or affected an attack since your last turn, roll a d4.
If you roll a 1, this spell ends.

You can end this spell as a fast action.

Suggested Backfire: You imprison your space within an arcane wall, which you cannot dismiss.

You create a sphere up to 15 ft. in radius which prevents any creature trapped within it, including yourself, from moving outside of it.
A creature may spend its action to try a DC 30 test of Strength to exit the sphere.
If a creature would be pushed or pulled out of the sphere, whatever is trying to move them may try a DC 30 test of Strength to force them out of the sphere.
You must be inside the sphere when you cast it.
Things from outside the sphere may enter it freely.

This spell ends if you are defeated, or you leave its area.
You can end this spell as a fast action.

Suggested Backfire: You cast the spell, but it only affects your space.