DarK_RaideR says:
I'm feeling the Jammer way more than the Half Orc (might be the hours I've sunk into Truck Simulator games) but also lack any XCrawl books. The Gamma Rules I found don't even include the Jammer (guessing that was in the beta release of the rules?) and only go up to level 2 for the classes they do include, so I'll need some help bumping my main man to 3.
I think gamma comes after beta, so maybe it was only on release. Here's your chart:

Quick overview of your class abilities:
HD: 1d8
Weapon training: Jammers are trained in the longsword, short sword, rapier, hand axe, dagger, spear, and crossbow. Jammers can wear any armor but wearing armor with an -4 or lower armor check penalty negates the AC bonus from their chosen weapon (see below).
Chosen weapon: At 1st level, the jammer picks one melee weapon from their trained weapon list as to be their chosen weapon. This weapon, once chosen, cannot be changed. Thereafter when fighting with their chosen weapon they receive an AC bonus equal to their class level.
Performance: At 1st level jammers are trained in one performance specialty. This can be practically anything with judge approval: freestyle rapping, electric guitar, slam poetry, blues harmonica, comedy, jazz crooning, etc. The check is 1d20+Per+level. Jammers choose additional performances at each level.
Disrespect: The jammer can use their performance specialty to lampoon, distract, detract from, and otherwise disrespect an opponent. The jammer spends a full round action using their performance specialty to disrespect their opponent and makes a Performance check. The opponent must make a Willpower save against a DC equal to the jammer’s Performance check. Failure means the opponent is disrespected for a number of rounds equal to the jammer’s level + Personality modifier (minimum of 1 round). While disrespected, the opponent takes a penalty to attack rolls, spell check rolls, damage rolls, and Willpower saves as listed in Table 1-11: The Jammer.
Devastating Attack: The jammers combat prowess and performance excellence merge in their devastating attack. If the jammer makes a successful attack against an opponent while they are disrespected, they add their devastating attack die to the damage, as indicated by Table 1-11: The Jammer. This can be a melee or ranged attack.
Lionize: The jammer can use their performance to bolster their allies, giving them a serious edge against their enemies. The jammer uses a single action to make a Performance check, making a particular ally the target of their lionization. If successful, the lionization benefits last for the jammer’s class level in rounds. Thus, a 2nd level jammer who successfully lionizes an ally gives their lionization bonus for 2 rounds. Check the Performance check against Table 1-10: Jammer Lionization to see its effectiveness. On any lionize check of a natural 1 the jammer flubs their performance that it actually gives their opponents a boost.
Mojo: Jammers earn a point of Mojo for every failed attack roll or spell check by disrespected opponents. In addition, the jammer has a special Mojo ability. Unlike members of every other class, the jammer has the ability to boost their ally’s attack rolls, spell checks, or skill checks with Mojo points from their own pool after the die roll.
Luck: Jammers add their Luck modifier to Performance checks. Jammers may choose to add their Luck modifier to their AC.