At 6th level, War Drummer skalds gain Improved Critical with clubs or greatclubs.
Skalds with the War Drummer archetype get the feat Improved Critical before anyone else. Instead of Scribe Scroll, they get the Deadly Rhythm (Ex) class feature. This has multiple benefits, such as:
At 6th level, the war drummer gains Improved Critical with the club or the greatclub as a bonus feat.
The Skald chooses either Improved Critical (club) or Improved Critical (greatclub).
Fighters, Brawlers, Gunslingers, Swashbucklers, Slayers, Avenger Vigilantes, and Oracles of Battle can get the feat at 8th level.
Fighters, Brawlers, Gunslingers. and Swashbucklers gain a bonus combat feat at 8th level. Since they have a BAB of +8, they qualify for Improved Critical, provided that they select a weapon for which they are proficient.
Prerequisite: Proficient with weapon, base attack bonus +8.
Slayers gain a Slayer Talent at every even-numbered level. If select Rogue Talent at 8th level, they can use it to gain the Combat Trick rogue talent, which can then be used to gain Improved Critical because they have a BAB of +8.
Similarly, Vigilantes choose a Vigilante Talent at every even-numbered level. If they chose the Avenger option for their Vigilante Specialization, then they will have a BAB of +8 at level 8, and can choose the Combat Skill talent to gain Improved Critical.
Also, if you multiclass between full-BAB classes, and your 8th class level would grant you a bonus (combat) feat, then you can get Improved Critical by 8th (total) level. Examples:
- Paladin 7 / Fighter 1 (choosing Fighter for your 8th character level)
- Ranger 4 / Slayer 4 (choosing Slayer for your 8th character level)
- Barbarian 3 / Brawler 5 (choosing Brawler for your 8th character level)
- Cavalier 6 / Fighter 2 (choosing either for your 8th character level)
And if you use the retraining rules, then any 8th level character with a BAB of +8 can pay a cost to exchange one of their feats for Improved Critical.
An Oracle with the Battle mystery has access to the Weapon Mastery revelation:
Weapon Mastery (Ex): Select one weapon with which you are proficient. You gain Weapon Focus with that weapon. At 8th level, you gain Improved Critical with that weapon. At 12th level, you gain Greater Weapon Focus with that weapon. You do not need to meet the prerequisites to receive these feats.
This revelation may be taken at any level, including those below 8th. As soon as the Oracle reaches 8th level, the revelation grants them the bonus feat.