Conjure Zyzx, Chaos Elemental

You call forth Zyzx, Chaos Elemental. When Zyzx is conjured roll a d4. On a 1 it appears in a Fire guise, on a 2 it appears in a Water guise, on a 3 it appears in an Earth guise, and on a 4 it appears in an Air guise. At the beginning of each of Zyzx's turns roll another d4. Zyzx will change to that element.

The elemental is friendly to you and your companions for the duration. Roll initiative for the elemental, which has its own turns. Zyzx will see you and your companions as friendly until one of you damages it, then it will see everyone as hostile. Zyzx will always attack the closest hostile creature.

Zyzx cannot be controlled, but you may use your bonus action on each of your turns to gain advantage on a roll for Zyzx.

While you have this spell prepared there is a chance that it will cast itself. Every time you cast a 1st level or higher spell, roll a d20. On a roll of 1 the original spell is cancelled and you cast Conjure Zyzx, Chaos Elemental instead. When this happens roll a d8. Whatever number comes up is the level at which Conjure Zyzx is cast. 

The GM has the elemental's statistics. Sample elementals can be found below.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, it will summon a different type of elemental based on the level used.

Sample Elementals