Jab → Jab → Hook → Haymaker
is these actions triggered by a single key?
For example. you spam A key.the character releases these actions in fixed order.and now you want to customize the order?
I’m not sure if I understand,because I didn’t play many combat games.
but If the above is the case.
I think you could use montage instead of state machine.(because I see you were talking about transition?)in my imagination I don’t see the need for transition.montage can automatically interrupt other animations.
as for implementation.
you could store an array of anim montages. treat the array as an inventory.
when spamming the attack key ,increase an integer,use the integer to get an animation to play.(you might want to figure a way to limit when it can be increased and when it resumes to zero)
and the player can buy,sell,swap action order,etc… operating the array would do the work.