Go forth and aid the weak!
Henzell says...
  1. Gives you two good mutations, one for each XL worth of experience you get after getting the mutation. The good mutation can be evolution again. Two levels. See also {devolution}.
  2. In older versions, gave you mutations as you gained experience. 40% random mutation, 40% random good mutation, 20% delete a mutation (strongly biased towards deleting a bad one). Every time evolution acted it had a 1/10 chance to delete itself as well. Failures die fast... (Mostly did very little in practice.)

Information based on master branch and the great LearnDB.
© Dungeon Crawl Stone Soup, 2010.