From the introduction:
The Heren Turambarion’s Compendium is organised in the same way as Decipher’s core rulebook, following it chapter by chapter. It starts with additional material for character creation, along with some suggestions that lower the power level of starting characters. This makes adventuring much more challenging, and prevents the characters from performing world-shaking deeds with merely one advancement or two. But the Compendium is by no way only about restrictions; it also offers a host of new, fun-to-use game mechanics and roleplaying opportunities such as the thirty-six new flaws. Also covered are rules for critical strikes, both for weapons and natural attacks of all kinds, and for damage-dealing spells. Players will also find the extended equipment lists most useful, for they introduce a broad variety of items and feature more balanced statistics for weapons.
A variety of house rules and variant rules for the game.