Free tables Natural 20 — skill checks

Natural 20 Table — Investigation Skill Checks, d20

A free d20 table for a natural 20 on a Investigation check in 5e. Twenty outcomes, from solid to legendary.

A natural 20 on a skill check is not a critical success in fifth edition — criticals apply to attack rolls only, and a 20 on a check is simply a 20. Which is why a legendary roll so often feels like nothing happened. This table gives it somewhere to land.

Twenty results written for Investigation specifically. A legendary Investigation roll has nothing in common with a legendary roll at anything else, which is why there are eighteen of these and not one.

Roll d20 when a player rolls a natural 20 on a skill check and succeeding quietly would be a waste.

Severity tiers

Each result names its tier, so you can see at a glance how bad a roll was without decoding a colour.

Solid 1–10 — Cleanly done, with something small to show for it.
Impressive 11–17 — Better than anyone expected. Momentum, or an obstacle gone.
Legendary 18–20 — Scene-shaping. The kind of success people repeat afterwards.

The table

20 results. Roll d20.

d20	Result	Tier	What happens
1	Found It	Solid	You find exactly what you were looking for, first try. No extra effect.
2	And Something Else	Solid	You also turn up one additional item or clue nearby, the DM's choice.
3	Left It Tidy	Solid	Nobody will be able to tell the place was searched.
4	Quick Work	Solid	The search takes a fraction of the time. The DM should say what that buys you.
5	Spotted the Mechanism	Solid	You identify a trap, catch, or hidden fastening here before it becomes a problem.
6	Ruled It Out	Solid	You establish with certainty that something the party suspected is not the case. That's worth knowing.
7	Methodical	Solid	You have advantage on your next Investigation check this scene.
8	The Order of Events	Solid	You work out the sequence of what happened here, and in what order.
9	Pointed It Out	Solid	One ally has advantage on their next Investigation or Perception check in this area.
10	Whose Hand	Solid	You determine who was responsible for what you're examining — by tool marks, handwriting, or habit.
11	The Hidden Compartment	Impressive	You find a concealed space nobody knew to look for, and what's inside it.
12	Disarmed by Understanding	Impressive	You understand the trap so completely that disarming it needs no roll.
13	The Missing Piece	Impressive	You identify what should be here and isn't. Its absence is the clue.
14	Connected Two Threads	Impressive	You link this evidence to something from an earlier scene. The DM should confirm the connection is real.
15	Read the Whole Room	Impressive	One search covers the entire area. Nothing here escapes you.
16	Proof	Impressive	What you find is not just suggestive but conclusive — enough to convince a sceptic or a court.
17	Set the Trap Back	Impressive	You can leave the evidence, or the trap, exactly as it was — and now it works for you instead.
18	Solved It	Legendary	You work out the answer to the question the party has actually been asking, not just this room's version of it. The DM gives you the solution.
19	The Thing Nobody Hid	Legendary	You notice something that was never concealed because nobody imagined it would be looked at. It changes the situation.
20	The One They'll Talk About	Legendary	Your reasoning collapses an entire line of the investigation. The DM should skip ahead: the party gets the conclusion now, and the villain's plan is exposed early.

Questions

Is a natural 20 a critical success on a skill check?

Not by the rules. Criticals apply to attack rolls. A 20 on a check is a 20 — which is why a spectacular roll so often produces a shrug. This table is the house rule that fixes that.

Does a natural 20 automatically succeed?

No. On an ability check there is no automatic success — if the DC is 25 and your total is 22, you failed with a 20.