In my on-going campaign to 'screw around with' (or "houserule") Crypts & Things I came up with a a couple of ideas to soup up the thief class, in line with the fighter class.
Because Crypts & Things aims to emulate the swords & sorcery oeuvre by making all characters "rogues", it almost makes the thief character class redundant.
As I'm aiming more for a game that replicates Hawk The Slayer - rather than every sword & sorcery setting - I'm trying to rein in the general roguishness, by restricting the bulk of thievery skills to actual thieves, while still keeping some aspects that 'work' for my game vision (such as everyone being able to backstab).
Below I present a couple of the changes I'm implementing: rogue specialities for thieves (echoing the 'combat styles' of Crypts & Things for fighters) and increased backstabbing damage for high-level thieves (based on a suggestion from Chris Freeman.
ROGUE SPECIALITIES: All thieves have access to the exclusive class skills of climbing, legerdemain, opening locks, perception, stealth and traps – in which gain a +3 on their Saving Throws (all characters have the climbing skill, but only barbarians share the thieves +3 bonus on Saving Throws).
Thieves have ‘specialities’ like fighters have combat styles. A thief starts at first level with a single speciality and then gains a new one at 4th level, 8th level, 12th level and 16th level. Unless stated otherwise, each may only be taken once.
1. IMPROVED CLASS SKILL: The thief gains an extra +1 bonus to any one of his traditional class skills (e.g. of climbing, legerdemain, opening locks, perception, stealth and traps). If taken a second time, the bonus must be applied to a different skill.
2. DISGUISE MASTER: The thief is a master of disguise, gaining +3 to saving throws to fool people if he has access to his trunk of make-up, wigs etc The success of improvised disguises, without the use of any props or make-up, is determined by a straight saving throw (without any bonus).
3. CON ARTIST: The thief has the gift of the gab and can talk his way out of any situation or convince people that what he says is true. This isn’t a magical ability though, so has limits – depending on his credibility and circumstances – but the thief gets to make his saving throws at +3.
4. LORE MASTER: The thief ‘knows things’, odd snippets of history and legend. When dealing with information concerning his home and its environs he can make a saving throw at +3 to know something useful, otherwise he makes a straight saving throw. The further he is from his homeland, the vaguer and more tenuous his knowledge will become. But it’s better than nothing.
5. FORGER: The thief can forge documents – as long as he has an original to copy – that will most people. He makes his saving throw, at +3, to create the forgery and they must make a 5d6 vs INT+LVL check to detect it (as long as he made his saving throw; otherwise it is a 3d6 check).
6. ESCAPOLOGIST: The thief can slip bonds and manacles (given enough time) if he makes his saving throw at +3. Certain chains etc may give negative modifiers to the roll, but he will always get a saving throw and have some chance of escaping.
7. VENTRILOQUIST: On a successful saving throw this thief is able to convincingly throw his voice, up to a range of (29 + LVL) feet. How the hearers react to the sound, of course, is up to the DM to determine.
8. POISONER: Anyone who uses a poisoned blade etc must make a saving throw to avoid accidentally poisoning himself (a stray drop in the eye, on the skin, on the lips, in an open wound etc), but this thief gets +3 on his saving throw because of his training.
BACKSTABBING: In Crypts & Things (pg 30) everyone can backstab with a bonus of +2 to +4 and rolling damage dice twice, however now thieves get better at it as they increase in level.
Roll damage dice three times
Roll damage dice four times
Roll damage dice five times