I was playing Rohan when the first 12 expansions were out, so it had Shadows and
Black Rider at that time, but the core would be pretty similar I assume.
Shadowplay +
Unheeded is a nice counter measure against corsairs, you can kill
Corsair Marauder as he is played with it and thanks to the discarded when played rule his game text won't take effect. Also both cards just generally combo well with horses and
LoI and such.
Birthday Present and
a Light in his Mind can be helpful too, but I don't like to bank on not playing against
Saruman's Power a lot, so bear that in mind.
I used to start with
Tall and Proud +
Swordthain, so I had access to both
Simbelmyne and
Shadowplay/
Unheeded on turn 1 without relying on draws.
I also consider
Leowyn a must for any rohan build, grants great cycling ability and much needed healing.