Arcane Elemental

Arcane Form. The elemental can enter a hostile creature's space and stop there. It can move through a space as narrow as 1 inch wide without squeezing.

Wild Magic Aura. Each creature that starts its turn within 30ft of the elemental's space must make a DC 14 Intelligence saving throw. If the saving throw fails by 5 or more, the creature must instantly roll on the Sorcerer's Wild Magic Surge Table. Otherwise, a creature that fails the save must only roll on the Wild Magic Surge Table if they cast a spell during their turn. Rerolling rolls of 99-100.

Innate Spellcasting. The elemental's innate spellcasting ability is Intelligence (spell save DC 14 , +6  to hit with spell attacks). The elemental can innately cast the following spells, requiring no material components:

At will: Control Flames, Mold Earth, Shape Water,Detect Magic, Mage Armor 

1/day each: Erupting Earth, Fireball, Lightning Bolt, Tidal Wave

3/day: Wall of Fire, Wall of Force, Wall of Ice, Wall of Stone, Wall of Water

Magic Resistance. The elemental has advantage on saving throws against spells and other magical effects.

Magic Strike. The elemental makes two spells attacks of the following magic strikes at random, decided by rolling 1d4 (reroll duplicates).

1. Fire Strike. Melee Spell Attack: +6 to hit, reach 5 ft., one target. Hit: 13 (2d10 + 3) fire damage.

2. Cold Strike. Melee Spell Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d8 + 3) cold damage. On hit, the target's speed is reduced by 10 feet until the start of the elemental's next turn

3. Lightning Strike . Melee Spell Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d8 + 3) Lightning damage. On hit, the target can't take reactions until the start of its next turn.

4. Magic Missile. Spell Attack, reach 60ft., four glowing darts of magical force appear. Each dart hits a creature of the elemental's choice that it can see within range. A dart deals 1d4 + 1 force damage to its target. The darts all strike simultaneously, and can be directed to hit one creature or several.