Instability (Mystcraft)

Instability refers to the hostility of an Age in Mystcraft, or at least as compared to the overworld. It can be as simple as a scorched surface that sets entities on fire (which can be caused by something as basic as orbiting closer to the sun) or an atmospheric difference that hinders players and not native animals, or as complex as meteor showers or spreading blocks of doom that either wipe out other blocks in the world or open sinkholes into the void.

In general, instability only happens if a world is either badly written, deliberately, or if it is greedy—if it contains extra riches and valuable resources.

Cause of instability
Occasionally, random things may be found in a world that provide players with extra resources; these extra resources will generate instability. An example of this would be Coal Tendrils. A Tendril is similar to a small cave system, but made from some material, typically wood, instead of air.

The more valuable the resource, as well as the more common it is, will determine the amount of instability.

Badly written worlds (if the Book Binder is used to make customized worlds) can also cause instability.

The most common source of instability will be oceans of some mod-added liquid. These will generally be unstable to the point that the world will just need to be abandoned.

Types of instability
Some of the possible instabilities are:
 * Blindness
 * Nausea
 * Crumble: Turns Dirt into Sand, ore into Stone (Diamond Ore turns into Coal Ore), and Stone into Gravel.
 * Black Decay: Generates black blocks that spread outward causing the blocks on top to fall into the void. This decay will not spread upwards, nor will it spread through air—however, it will spread downward and collapse down through a cave or opening. The end result of a world with Black decay, and not white decay, will be a skyblock-like near void.
 * Red, Blue, and Purple Decay: Turns the world into the decay block. Different colors spread faster through different types of materials, for example, purple spreads fastest through liquids. These will spread upwards, and very slowly through air. If black decay is underneath them, it will very likely turn that area into void.
 * White Decay: Turns the world into a decay block that damages any moving mobs, including the player, however by standing still players will remain unharmed. This spreads too fast to be removed without some sort of massive automated removal (see Bound Pick from Blood Magic). This spreads upwards, and through air and bedrock at an alarmingly fast pace. This decay will overpower any of the other standard decays.
 * Enemy Regeneration: Hostile creatures have passive health regeneration.
 * Erosion: Same effect as Crumble though only occurs around fluids.
 * Explosions: Frequent spontaneous explosions occur randomly throughout the world.
 * Mining Fatigue
 * Hunger
 * Lightning: Causes lightning storms that burn their hit positions.
 * Meteors: Frequent meteors fall from the sky, destroying blocks, creating large explosions and fires while dropping ores. It will destroy all blocks, even bedrock, given time or a chunk loader.
 * Poisoned Surface: Poisons players while walking on the surface
 * Scorched: All mobs, including the player, catch on fire when exposed to the sky.
 * Slowness
 * Weakness

Most potion effects can be avoided by taking shelter under cover. The exceptions are mining fatigue and hunger.

Additional fun can be with the More Mystcraft Decays mod. The current version is SSP/LAN only.