No true infinite musou trick but loads of ways to keep that gauge filled and ready. Grab dragon amulet and elixir first since they'll boost duration and charge speed then hunt down those musou +10 upgrades from supply units whenever you spot em. Way of musou item lets you trigger true musou anytime, not just at low health which is super handy for tough fights

Keep an eye on your health cause true musou kicks in automatically when youre hurting and gives you those sweet invincibility frames perfect for dodging lu bu or other nasty officers. Stack up hits on grouped enemies to fill that gauge fast and maybe interesting zhou yu's moves are great for this cause of his wide sweeping attacks. Good tip save your musou for either clearing crowds or taking down officers since thats where itll help most just remember no move lasts forever so make it count