Since our class is basically randomly chaotic on Legion why not add a Rainbow fire on it?
Could be a random chance of a random color on a random number of spells.
Imagine the possibilites on randomly paint all your raid with a powerpuff rainbow Rain of Fire with random colors dropping randomly of the Sky.
And why not Dreadsteed being Randomly transformed into a Rainbow Evil-Fel Horse with Rainbow fire ?
Even or Imps could be summoned on random different colors.
And when on PVP one Rainbow fire warlock meets another Rainbow fire warlock they could form a true rainbow between your deadly rainbow skills.
This would be the dream of every Blood Elf Warlock, Glamorous.
Infracted - Woz