Unstable Volcanic Eruption

You rip an unstable hole into the quazi-elemental plane of magma which erupts lava that crashes down on the selected area. Each creature in that area must make a Dexterity saving throw. On a failed save, a creature takes 1d8 bludgeoning damage and 3d8 fire damage and is knocked prone. On a successful save, a creature takes half as much damage and isn’t knocked prone. The lava then spreads out across the ground in all directions, igniting flammable objects within 30 feet of it, and quickly hardens and cools.

Anyone knocked prone by the lava must make an additional strength saving throw to avoid being restrained by the magically hardening lava. On a failed save, a creature takes another 3d8 fire damage and becomes restrained. They may repeat this save each turn, but they do not take any additional damage. On a successful safe, they take half as much damage, and are able to extract themselves in time.

After one minute, the hardening lava closes the tear and ends the spell leaving a hardened mound of lava rock.

In order for the caster to maintain control of the violently unstable weave that holds the rift open, they must succeed on a DC 10 constitution saving throw when the spell is cast. If concentration  is broken, they lose control of the rift, which tears open wider rather than closing. The volcano will last 1d4 days, and can disgorge creatures from the plane at the DMs discretion.