Chaos is an uncommon card for The Defect that provides a cheap but unpredictable source of Orbs. Upgrading Chaos causes it to Channel two Orbs instead of one.
As the art suggests, all four Orbs - Lightning, Frost, Dark, and Plasma - can be Channeled using Chaos.
Chaos is one of the most efficient sources of Orbs available to The Defect, and the only reusable way to Channel multiple Orbs. If your deck benefits from loading up many Orb slots or doing a lot of Evoking, Chaos will rarely disappoint.
In addition, Chaos is a useful "duct tape" card to smooth out any Orb-related deck. For instance, if you picked up a Thunder Strike but can't find a Ball Lightning to power it, an Chaos can serve the same role.
It's also a cheap, if unreliable, source of Plasma Orbs. Decks with many X-cost cards can make the most of these Energy windfalls.
That said, Chaos does introduce some variance. You can't count on it to produce the specific Orb you need, and bad rolls will occasionally end your run. When offered a Chaos, consider the percentage of good or neutral outcomes versus the percentages of "bricks".
Upgrading Chaos is highly recommended. Not only does the upgraded card double the effect, it also doubles the odds of getting the Orb you need.
Chaos has an obvious synergy with Compile Driver. The card draw provides much-needed "gas" when Chaos feeds you Plasma Orbs. Note that this increases the variance of the deck, as Compile Driver is significantly weaker if you only have one type of Orb.
The card works well with both Consume and Capacitor. The former can turn an upgraded Chaos into a guaranteed powered-up Evocation. The latter allows you to stack up more Orbs so you can cast Chaos without prematurely Evoking your Dark Orbs.
While Chaos doesn't explicitly synergize with Rainbow, the two cards share synergies and coexist nicely.
Chaos is a terrible choice for Dark Orb decks. It will often prematurely Evoke a Dark Orb, effectively making it a Curse for most of the game.
The card is risky but useful in Frost Orb decks. These builds often aim to stack up enough Frost Orbs to completely neutralize enemy attacks, which Chaos undermines by bumping off Frost Orbs. That said, Chaos does generate 10 block for 1 Energy in these decks, in addition to whatever benefits the Orbs provide.