From publisher blurb:
Variants, house rules, and other rules changes made at the table have been a staple of tabletop roleplaying games for as long as there have been tabletop roleplaying games. This document analyses variants and optional rules published in the Player’s Handbook and the Dungeon Master’s Guide, adds several additional rules variants, and offers advice on why you should and not use each optional rule and variant.
What is in this document?
Analysis of 42 variant and optional rules taken from the Player's Handook and the Dungeon Master's Guide
27 new variant rules, some of which are adapted from previous editions or from other tabletop RPGs, but many of which are completely new
Discussion of all included variant rules explaining potential issues and reasons why you should and should not use each option