My local play group is setting up and event for late July and I'm thinking of starting up Rohan for the event. We have two restriction, no heros bast HoF and no model above 100 points. My list that ive written up is as follows.

Déorwine
-horse
9x Riders with throwing spear
Erkenbrand
-horse
-HoF
5x Riders with redshield and throwing spear

Any advise on the list would be greatly appreciated.

Considering the hero restrictions, I'd say you are in decent shape. Obviously Theoden would be the go to choice for getting to use the "Arise Riders of Theoden" rule, but he isn't an option and you have got probably the best heroes for the might and secondary effects from the lesser heroes here.

In terms of troops, I think you've got a decent set here. Just massed throwing spears and riders to overwhelm the enemy. A proper banner might be worth squeezing in to get rerolls for your heroes and to spread out the area of rerolls you have cross the battle field. It would cost two riders to get though, so it up to you if you think it's worth it.

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"Draw your sword with a heavy heart, but swing it with a heavy hand"

I did write up a second list that more joke around friendly

Erkenbrand
- horse
10 redshield with spears
Knight Captain of Dol Amroth
-horse
-lance
3 knights of Dol Amroth on horse with lance