It's a perennial favourite activity of mine (and many other DMs) to mess around with the thief class in D&D. (Well, ok, it's a perennial favourite activity to mess around with any and all classes in D&D, but today I'm talking about the thief.) People have a lot of various beefs (beeves?) with the class. My personal beef is that I like to stick with four core classes but that I want to mix in the extra abilities of the assassin, bard, thief-acrobat, and anything else that comes to mind, to produce a single unified "dodgy person who does sneaky stuff" type class.
Previous thoughts along these lines: here, here & here.
I'm building up to run a Dark Sun inspired campaign with Labyrinth Lord, and have in mind that it'll involve lots of sneaky infiltration and subterfuge, so it seemed like high time to revisit the "dodgy person who does sneaky stuff" class.
Here's my latest take on it. (Note the inclusion of freely distributable percentage points -- a nod towards AD&D 2e. I'm planning on adding a few other 2e type features to the campaign, weapon proficiencies, for instance.)
The rest of this post is designated Open Gaming Content according to the Open Gaming License.
Prime Requisite: DEX
Hit Dice: 1d4
Those adventurers who live by stealth, deception and wits are known as infiltrators. Some infiltrators are self-made, having learned their trade in the back-alleys and marketplaces of the great cities, while others are members of guilds and have studied under master thieves, spies, scouts and assassins.
Infiltrators use the thief experience, saving throw and attack tables, and are able to use leather or studded leather armour, all one-handed weapons and light missile weapons (all except longbow and heavy crossbow).
They have a number of skills unique to this class, which advance as the character increases in level. A 1st level infiltrator begins with a 0% chance of success in all skills, but gains 100 percentage points to distribute as he wishes between them. At each subsequent level he gains a further 20 percentage points to improve his skills. No skill may be increased beyond 98%.
Acrobatics: This skill can be used to perform feats of acrobatics such as leaping, vaulting, flipping, balance, and so on. The Labyrinth Lord may specify a penalty to the roll for extraordinarily difficult feats. An infiltrator may also use this skill to reduce falling damage by half.
Assassination: When performing an attack by surprise (either during a surprise round of combat, or due to use of hide in shadows or move silently), the character has a chance of being able to instantly kill his victim. If the attack succeeds, a percentage roll is made against the character's skill with assassination. If the roll succeeds, the victim must save versus death or die immediately. If the save succeeds, the attack causes double normal damage (which may in turn be enough to kill the victim). Note that for an assassination to succeed, the infiltrator must be able to attack a weak point of the victim (the throat or heart, for instance) – certain situations or targets may make this impossible, at the Labyrinth Lord's discretion (for example, undead creatures generally lack any such weak points).
Climb walls: Infiltrators are skilled climbers, and never need to make rolls to climb under normal circumstance (ladders, ropes, trees, etc). This skill enables the character to climb vertical surfaces with only small handholds, such as brick walls or cliffs. The skill check may be penalised due to exact conditions (slipperiness, darkness, etc).
Decipher script: The infiltrator is skilled at cracking coded messages, or deciphering small fragments of text written in foreign languages, such as may be found on treasure maps. This skill may also be used at a -10% penalty to attempt to cast spells from magic-user scrolls. In this case failure indicates a misfire of the spell.
Disguise: All characters may at times attempt to disguise themselves, with success determined by the Labyrinth Lord. This skill gives the infiltrator a backup roll if the Labyrinth Lord determines that a disguise is ineffective. A successful roll means that the character goes unnoticed.
Find/disable mechanisms: Characters of any class can search for hidden mechanisms to activate traps or secret doors, having a 1 in 6 chance of success. An infiltrator also gains a percentage roll with this skill. With the appropriate tools, this skill can additionally be used to disable or bypass small mechanisms such as sprung-needle traps or locks. Using this skill takes one turn.
Hear noise: All characters can listen at doors to detect sounds beyond, having a 1 in 6 chance of success. An infiltrator with this skill gains the normal 1 in 6 roll in addition to a percentage roll with this skill. Using this skill takes one turn.
Hide in shadows: Infiltrators are masters of concealment, and do not need to roll to hide under normal circumstances (behind statues, screens, undergrowth, etc). They can use this skill to attempt to hide when no cover is available beyond deep shadows. The character always thinks he is successful.
Move silently: Infiltrators are experts at creeping quietly, and do not need to make any roll to sneak under circumstances where absolute silence is not required (for example in a noisy environment). A successful roll with this skill means that the infiltrator is able to move unnoticed in situations where the slightest sound would give his presence away. The character always thinks he is successful.
Pick pockets: This skill can be used to artfully extract small objects from the possession of others.
Poison lore: An infiltrator can use this skill to detect and identify poisons (on weapons, in food, etc), and to create them. Each type of poison (q.v.) is rated with a difficulty to detect or manufacture, which is applied as a penalty to the skill roll.