We have other simple tools we can keep in our heads that help us run a fun D&D game. As long as your drive is to make the game as exciting as you can, you have full authority to make these sorts of changes. If this feels like cheating to you, consider hanging onto the game with a looser grip.
We can do all of these while a battle is taking place. We can increase or reduce a monster's hit points, damage, or the number of monsters in a battle to easily change the threat of the battle. We have other tricks we can use to improvise the challenge of a combat encounter without resorting to any charts, tables, tools, or anything else.
For example, my encounter building guidelines are intended to give DMs some rules of thumb to quickly gauge whether an encounter might be inadvertently deadly. This means learning how to do a lot of the prep and improvisation work of D&D in our heads. Here at Sly Flourish I believe firmly in helping DMs develop the tools change up our game without having to spend a lot of time or carry around a lot of extra books. New to Sly Flourish? Start Here! Building Legendary D&D Monsters in your Head
