Elemental Breach

With a gesture you tear reality asunder. Targeting a point within range you open a circular portal 30ft in diameter, linking to one of the four elemental planes, facing in a direction of your choosing. Substance from that plane is forcefully pushed out, striking every creature in a 30ft wide, 120ft long line originating from the portal, after which the portal closes and any remaining elemental material vanishes, unless otherwise noted.
You choose which element upon casting the spell.

Air: A whirl of slashing and buffeting winds jumps from the portal. Each creature in the area must make a dexterity saving throw or take 20d10 slashing damage and be pushed 60ft away from the portal. On a successful saving throw a creature takes half as much damage and isn't pushed. Objects that are huge or smaller and aren't being worn or carried are also pushed 60ft. 

Earth: An avalanche of stone comes pouring out of the portal. Each creature in the area must make a strength saving throw or take 20d8 bludgeoning damage, be knocked prone, and restrained by the stone, enough stone remains to continue this effect. Structures also take this damage. On a successful saving throw, the target takes half as much damage and isn't restrained. A restrained creature can make an additional saving throw at the end of each of its turns, ending the restrain on a success. 

Fire: A sudden blast of flame flies from the portal. Flammable objects in the area are ignited and each creature in the area must make a dexterity saving throw or take 20d8 fire damage. On a failed saving throw, the target will catch on fire and take an additional 10d8 fire damage at the end of their next turn, at which point the fire will douse. On a successful saving throw, the target takes half as much damage and is not ignited. 

Water: A tidal wave of freezing water blasts from the portal. All fire in the area is doused, and each creature in the area must make a constitution saving throw or take 20d10 cold damage, or half as much on a successful saving throw. For 1 minute after, the ground of the spell's area is coated in ice and counts as difficult terrain. At the start of each turn a creature attempting to move on the ice must make a dexterity saving throw or fall prone.