Combat in 5th edition is a loop: everyone rolls for order once, then takes turns until the fight ends. Almost every action resolves the same way — roll a twenty-sided die, add a modifier, compare it to a number. Once that pattern is familiar the rest is detail.
When a fight starts, everyone rolls a d20 and adds their Dexterity modifier. That is initiative. Highest goes first, then down the order, then back to the top for the next round.
A round is about six seconds of story time. Order stays fixed for the whole fight, so you only roll initiative once.
Each turn you may take one action, one bonus action if something specifically grants one, and movement up to your speed. You can split movement around your action — walk, attack, keep walking.
Common actions:
You also have one reaction per round, used outside your turn — most often an opportunity attack when an enemy walks away from you.
To hit something: roll a d20, add your ability modifier and your proficiency bonus. If the total meets or beats the target's armour class, you hit and roll damage.
Armour class is just "how hard is this to hit" — a single number from armour, shields and Dexterity. Meeting it exactly counts as a hit.
A natural 20 on the die is a critical hit: roll your damage dice twice. A natural 1 always misses, however large your bonus.
The most elegant rule in the edition. With advantage, roll two d20s and take the higher. With disadvantage, take the lower.
They do not stack — any number of sources still gives one instance — and if you have both at once, they cancel and you roll one die. Advantage is worth roughly +5 in practice, which makes it far more valuable than most flat bonuses.
Attack rolls are you trying to affect something. Saving throws are you resisting something that is already happening — a fireball, a poison, a spell that would charm you.
Roll a d20, add the relevant ability modifier, add proficiency if your class is proficient in that save, and compare to the effect's difficulty class. Many spells deal half damage on a successful save rather than none.
Damage subtracts from hit points. At 0 hit points you fall unconscious and start making death saving throws on each of your turns: a plain d20, no modifiers.
This is why healing someone at zero matters more than topping up someone at half — it resets a countdown.
Fights end when one side is beaten, flees, or surrenders. Not every encounter has to finish with everything dead, and tables that remember this tend to have better fights: enemies who run, negotiate, or drag their wounded away make a world feel inhabited.
MONOLITH tracks initiative, hit points, armour class and death saves for everyone at the table, and gives each player a card each round for movement, action, bonus action, reaction and dialogue — so a round resolves together rather than one person at a time while everyone else waits.
You still roll the dice. When a check is called for, the tray opens and the result is yours. See also what an Autonomous Dungeon Master does.
Also: building a
5e character step by step →
Also: running 5e with only two people →