Some spells I thought up:
Confusion: a spell like thunderclap.
Transform Self: Change yourself into a random creature. Could be as strong as a dragon but could easily be as weak as a sheep.
Transform other: Transform self but casted at the enemy.
Dice: random effects to stats, (temp).
roulette: same as dice but works on others.
Winds of Change: Changes the terrain randomly of current room. (Long cast duration).
Redirecting Fate: Randomly adds and removes effects. Effects could come from other classes's spells.
i'll add more if I think of anything else.
I think you're confusing Chance and Chaos. Randomness, while a facet of Chaos, is not Chaos in its entirety. I'm looking not so much at having spells with randomized effects, but rather more what Mya was suggesting, in the possibility of spells with a backlash. Like I said, my view of Chaos Mages is a hybrid class with an innate magic that is extremely powerful, and barely controllable. To give you an idea, here's a preview of what I'm working on.
Minor Ritual -> Ritual -> Major Ritual -> Master Ritual
There will be four paths - Protection, Augmentation, Combat, Destruction (ranging in power from weakest to strongest, and in safety from safest to most dangerous). As far as actual use goes, the minor ritual will be a chii-like skill that is enabled via the command "ritual". The base ritual will then be activated via the "release" command, or further chaos can be stored using the "store" command to activate the more powerful rituals. So to make it a little clearer, here is the destruction path (or what I have so far).
Destruction: Chaotic Touch -> Atrophy -> Entropic Infection -> Disintegration
Chaotic Touch (Passive)
At the first circle of their training, a Chaos Mage focused on Destruction can learn to imbue his hands and extensions thereof (namely weapons) with a small force of Chaos. This force, based on the Chaos Mage's own strength, can cause harm to the Mage's opponent in battle. However, the force may also attack its caller, harming the Mage instead.
Atrophy (Release)
A Chaos Mage of the second circle may focus the force of Chaos in their hands, causing it to directly attack the muscles of their foe. This results in the accelerated deterioration of their opponent's musculature, which can greatly weaken and enfeeble the Mage's enemy.
Entropic Infection (Store one, Release)
In the third circle of their training, a Chaos Mage learns how to focus Chaos within the body of their foe. However, the unitiated of Chaos often find themselves lacking the ability to withstand this force. As a result their body turns on itself, attacking the cells infected with the Chaos in an attempt to get rid of them. It also weakens the foe's ability to fight off other infections, as their immune system is focused on attacking the disease at hand. (causes a temporary plague effect, and a longer lasting -spellsvs effect)
Disintegration (Store two, Release)
Upon completing the fourth and final circle of their training, a Chaos Mage is able to create a pseudo-sentient entity out of pure Chaos. This entity, unlike the entropic infection, enters the victims body and takes complete control. After several hours of incubation, the monstrosity savagely turns its host upon themself, causing massive damage and possibly killing them outright. However, this ability is not without its dangers. When meddling with such powerful forces, a Chaos Mage risks their own safety, for the Chaos may turn on them instead.