The only way to make raid warbands that aren't mounted/ranged more challenging is having them oneshot (instant-death effect) with every hit they do, and even than it'd be possible or even easy to solo them, and that oneshot will just punish you for lagging out for a second.
Just the way mounted combat works makes that the standard difficulty tricks (more morale/damage) just don't work.
Cledwun is a mounted warband with ranged mounted adds that use slows. So that warband has mechanics that ensure they can actually hit players, which makes it much harder than not getting hit at all of course.
But even with those mechanics, with the current MC system, you can't make a true raid warband. Most warbands can be completed in a 3man even if they are set to be really hard. I think actual raid content with mounted combat needs to be instanced, so things like large-scale positioning can matter. Having a raid scatter over an entire zone to make sure some mobs don't reach a certain spot etc.
For some more interesting content, there are also some more abilities needed for classes in mounted combat:
- Corruption Removal
- Effect removal
And of course DPS and healing skills need some reconsidering on base skills since the foot-traits no longer work.
Once that is possible, there can be things like corruptions that on expiration, kills everyone's steed within 25m range. Inductions that put a +200% incoming damage debuff on you. Mobs putting poisons on you that oneshot on expiration. Mobs should also have the ability to re-mount just like players (which can also be interrupted).
~Dwarrowdelf (Bomb Squad)~
Freeps: Vulcwen (R8 LM), Vulciel (lvl 100 RK), and some lower level alts.. Creep: Shadowweb (R6 spider)
My ideas on how LM should be: [url=https://www.lotro.com/forums/showthread.php?543323-LM-revamp-reconsidered]LM Revamp reconsidered[/url]