Nerf 3.1.3

Chaos Bolt: This spell no longer ignores damage reduction effects of the target.

That sucks, but reading more into it, it still pierces absorption and resistances as clarified by Ghostcrawler:

Cheat Death is an absorption. So Chaos Bolt can still pierce it.

Cloak of Shadows is a resist. So Chaos Bolt can still pierce it.

There are four basic categories of spell resistance here:

• Immunities -- things like Divine Shield. Chaos Bolt will not affect these.
• Damage reductions -- things like Barkskin. Chaos Bolt affects these currently, but not in 3.1.3.
• Absorptions -- things like Power Word: Shield. Chaos Bolt will continue to affect these.
• Resistances -- things like Cloak of Shadows. Chaos Bolt will continue to affect these.

So, not as bad as it originally sounded...