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This chapter is perhaps the most disparate and fragmented of all the chapters in this book. On the following pages you’ll find a variety of variant systems dealing with armor and defense, combat, damage, death and dying, heroic action, facing in combat, and even the most basic activity in the d20 game: rolling dice.
No DM, no matter how enterprising, could realistically hope to include all (or even most) of these variants in the same game—nor should he. In stead, the DM, working with the players, should pick and choose a small number of variants to add, weighing carefully how each one interacts with the rest of the rules used in the game. Try adding the variants one at a time, so that you can assess each one’s effect individually, rather than stacking a half-dozen new rules options onto the game simultaneously.
In some cases, the text notes how some variants might work well (or poorly) when combined in the same game. When used along with the DM’s good judgment, this advice can help the DM create a “suite” of variant rules that dramatically change the feel of his campaign.