Optional Feats Rule
It is possible to forgo taking the Ability Score Improvement feature to take a feat of your choice instead as described on page 165 of the Player’s Handbook
Optional Loyalty Rule
Some NPCs will use the loyalty rules described on page 93 of the Dungeon Master’s Guide to determine how far he/she will go to protect or assist the players.
More Difficult Identification Variant
It is not possible to detect magic or identify without the use of magic or through experimentation, as described on page 136 of the Dungeon Master’s Guide.
Mixing Potions Variant
It is possible to mix magical potions for unpredictable results as described on page 140 of the Dungeon Master’s Guide.
Automatic Success Variant
If you are very good and skilled at something, you might automatically succeed without having to roll a check. As a rule of thumb you succeed if the DC is 5 lower than the required ability check, and if the DC is 10 or less if you are proficient in the skill or tool. See page 239 of the Dungeon Master’s Guide for more information.
Optional Flanking Rule
A creature gains advantage on attack rolls against a common enemy as described on page 251 of the Dungeon Master’s Guide. When in doubt, trace an imaginary line between the center of the creatures’ spaces. If the line passes through opposite sides or corners of the enemy’s space, the enemy is flanked.
Optional Diagonals Rule
Moving diagonally costs 5 feet and then 10 feet of movement as described on page 252 of the Dungeon Master’s Guide.
The following actions, described on page 271-272 of the Dungeon Master’s Guide, is included in the game:
- Climb onto a bigger creature
- Shove Aside
When a creature takes a critical hit, drops to 0 hit points without dying, or fails a death saving throw by 5 or more, he/she sustains a lingering injury as described on page 272 of the Dungeon Master’s Guide.
Monsters and NPCs might flee under certain circumstances as described on page 273 of the Dungeon Master’s Guide.