Another expansion for Godeater is out, with a ton of crunchy OSR goodness for all your games. The Wild Magic Compendium is a treasure trove of random magic effects, mutations, and strange magical entities, designed to give GMs easy ways to throw consequences and complications into their adventures.

It includes:

• 100 Unique and characterful magical miscast effects, graded by severity and ranging from a rain of ancient coins to summoning the manifestation of death itself. 
• 100 Unique mutations, little quirks that a character might slowly accumulate as they explore irradiated god-entrails - or whatever weirdness is present in your own game setting.
• A system for performing magic through communion with local animistic spirits, turning magic into a game of diplomacy and historical research.
• A system for summoning demonic Principalities from the Dreg planes - if you can control them, of course.

There's a free sample of 60 miscast effects, and you can buy the whole pack for a tenner. The core rules are available here, completely free, and there are other expansions for items and rituals available - all ready for your extraplanar expeditions!