THE ANSWER
Horde Siege combines three squads of four in PvE. The September 30 launch notes increased invasion and higher-difficulty pressure while reducing some Weapon Part rewards. No official class-level threshold for leaving Rookie is established.
Class names are a starting point
The announced class roster is useful for arranging a conversation with your group. It is not enough to establish a best class, optimal composition, perk order or weapon build.
Specific bonuses, cooldowns and damage values need direct evidence before they become recommendations.
A practical squad briefing
Kingy preparation advice · not a tested gameplay procedure
Agree who will call objectives, who watches the route back and how you will signal a downed teammate. Keep those responsibilities flexible while you learn the actual class abilities.
After a run, note where the squad became separated and which objectives caused confusion. That is more useful feedback than changing every piece of equipment at once.
What changed after the beta
The Coalition says all invasions and the Commander and Allfather difficulties became harder. It adjusted Repair objectives and Medic stim duration, increased equipment and Squad Perk Energy costs, and reduced the impact of some Squad Perks.
Weapon Part rewards for invasion participation and stockpiles were reduced. The Prototype Lancer can execute Boomers, Flayers and Grinders at a lower health threshold. The notes also describe objective-start, completion, enemy-pathing and lobby fixes. They do not provide a new reward table or a recommended class level.
When should you leave Rookie?
Kingy preparation advice · not a tested gameplay procedure
Use your current build and squad results, not a community level number. First confirm that your squad can complete its assigned objectives, recover from a failed invasion and afford the equipment it actually uses. Compare the displayed reward and cost on the next difficulty before committing a long run.
Kingy has not measured class-level breakpoints, post-launch reward rates or the success rate of a particular squad. Record class levels, perks, difficulty, completed objectives, Weapon Parts and failures across repeatable runs before calling one transition point reliable.