Liar, Liar, Pants on Fire!

©2016 Bethesda Softworks (ZeniMax Media)

At least in D&D BECMI, Deception is just a Charisma-based skill. It’s a simple way to handle it. I wanted to expand on this. Lying is as much a skill as it is an art (for some characters), but it should involve the listener, known as the “mark.” Some people are just bad liars to begin with, but a bit of experience can improve one’s chances.
            Let’s first uncouple Deception from Charisma and treat it separately. Roll 3d4 for the base lying skill. This should yield an average lying talent of 7-8 vs. d20 skill checks (a roll of 1 always succeeds; a roll of 20 always fails). Then apply Tier 1 modifiers to the liar’s base skill score:

In Sooth! Thou dost mangle the truth

with a most clumsy tongue.

Tier 1 Modifiers (Liar Only)
−3 for paladins
−1 for mystics
−1 for lawful* characters other than paladins (*) LG in other game versions.
+1 or more for a well-crafted/roleplayed and credible tale with verifiable evidence
−1 for a lie greater than a trivial untruth
−2 for a bigger and questionable lie
−3 for a tall tale

Tier 2 Modifiers (Liar and its Marks)
+/−1 for every 7 experience levels or HD (so, at levels 7, 14, 21, and 28)
+/−1 to 3 for one of the highest of Charisma, Intelligence, or Wisdom attribute bonuses
+/−2 for thieves and “roguish” characters in general (incl. bards and courtesans)
+/−2 with the Deception skill or equivalent
            Tier 2 bonuses apply to the liar. Penalties reflect the mark’s discernment.

Example: A level 1 thief with a base skill score of 7 attempts to fast speak while facing a red dragon. The thief’s modifiers are −3 for tall tale, +2 for the thief class, +2 Charisma bonus, and +2 for the Deception skill, for a total of +3. The mark is a 15 HD red dragon with a Deception skill as well, yielding a −4 modifier for the thief’s tall tale. The final modifier is therefore −1. The thief needs to roll a 6 or lower for the lie to succeed. The same attempt against an orc would require the thief to roll 11 or lower.

Thou hast no more truth in thee than a stewed prune.

Other Factors
             Liars should incur a −2 Tier 1 penalty when facing NPCs who commonly deal with fraudsters and deceivers (such as constables, bounty hunters, bailiffs, magistrates, inquisitors, guards, tax collectors, nobles, household courtiers, merchants, guild wardens, clerks of the markets, old beggars, vagrants, bandits, pirates, smugglers, etc.).

Fie upon thy false tongue!

            The number of marks present may also pose a challenge. In a group of 2-3 marks, roll a check for the one hardest to fool. For a larger group, use the most representative mark and add a −1 penalty to the liar for the first 10 marks, −2 from 11 to 30, −3 from 31 to 100, −4 from 101 to 1,000, or a −5 for more than 1,000.

Methinks thou dost protest too much.

            If new evidence comes to light that may cause a mark to question an earlier deception, the liar must roll a new check with a cumulative −2 penalty for each new clue uncovered (the DM does so if the liar is unaware of the event). If verifiable evidence obviously refutes a lie or a check fails at any point, the mark should react accordingly.

Go to! Thy tongue outvenoms all the worms of the Nile.

Reactions
            The DM should adjudicate reactions as in the normal refereeing process. The extent of a miffed mark might reflect the total penalties involved in the failed check, as follows:

Zero: Shrugs and is disappointed; −1 reaction penalty (and −2 Tier 1 penalty)

−1 to −3: Is mildly offended; −2 reaction penalty (and −3 Tier 1 penalty)

−4 to −7: Is angry and seeks retribution; −3 reaction penalty (and −4 Tier 1 penalty; may warn acquaintances about the liar)

−8 or worse: Is furious and seeks personal revenge, legal or otherwise; −3 reaction penalty (will never trust the liar again; may post a bounty for the liar’s head, sends minions after the offending character and known associates, etc.)

Speak, sir, and tell me once again what brought
thy hidden purpose to my lonely roof.