deuxhero
Arcane
If it is "Mounted Combat", that would be near automatic inclusion for a few other things. Cavalier (and maybe Samurai, a glorified archetype) would be obvious since their abilities are utterly basic aside from mounted combat. Battle Herald prestige class would essentially be automatic with that and mass combat in. Paladin gets to choose between a mount and weapon buffing in PnP so that would be added. There's a barbarian archetype that gets a mount and some rage powers to support it, so that would go in.
Still, I can't imagine how they'll do mounted combat in RtWP. The big thing about mounted combat is movement, and RtWP sucks at that.
Still, I can't imagine how they'll do mounted combat in RtWP. The big thing about mounted combat is movement, and RtWP sucks at that.