With talk of new DLC being relatively close, I figure now would be the best time of any to return and throw out a reminder about some previously discussed mechanics
that need adjustment, either for the sake of balance, ease of use, and/or clarity:
1) Crumbling: Longer story short, undead units don't take enough damage from crumbling in exchange for their psuedo-unbreakability (only 11 dmg/second), specifically in the case of the Vampire Coast and Tomb Kings, but their greatly decrease leadership can also lead to situations where a unit with decent health that should rally will continue to crumble because the crumble damage keeps their morale from recovering. A suggested solution would be to increase the damage crumbling deals (i.e. double the damage), but increase the leadership on most undead units by 5-10 (with perhaps additional buffs for the Vampire Counts undead if this change proves crippling to them).
2) Stealth and detection: This mechanic is in desperate need of clarity. Specifically, it would help significantly if there was the ability to see a unit's detection ranges (like there currently is with firing arcs), one indicating the detection range against stalk/hidden units and a second one doing the same against unpotable units. Just give the option to toggle it on and off like with most of the in-battle information.
3) Forest Stalker/Aquatics: Long-story short, Forest Stalker encourages tree blobs due to the MD buff it provides. As many people have advocated, this bonus should be changed to literally anything that doesn't make fighting in trees massively advantageous for those with this bonus: a speed buff or something similar would do well. Likewise, aquatics should be changed similarly for both consistency and balance (aquatics gives a unit a 40% MA and MD stat swing against opponents in swampland).
4) Unit Formations: Were in previous total war games, surprising that it's absent from this one. The result is that loose formation is somehow superior to tight formation in all circumstances (something that defies IRL and previous TW logic) and units can't change formation. It would be nice to instead have the option on most units toggle between loose and tight formations, while reinstituting drawbacks to each like in the previous games.
5) Vortexes: A little indicator for where the vortex will go first would be nice, as well as being able to control the initial direction (just the initial direction) would go a long way to make these spells better.
6) Trait Limit: This one is mostly focused on single player, but still relevant to game balance. Basically, there is a limit to how many traits a Lord can have, and once hit a Lord can gain no more traits. There is literally no reason for this to be the case: from a balance perspective, acquiring the traits requires time investment insofar as by the time the Lord would start exceeding the trait limit, they're most likely lvl 40 and the small power boost each trait would give would be negligible at that point (as the Lord is probably already optimized and winning most battles at that point). Likewise, the whole point of the system is to add something fun to hunting down legendary lords: a trait limit undermines that purpose, especially when traits cannot be removed and you can't easily see how many traits a lord has. Unless there is a coding limitation or something similar, there isn't a good reason to limit the number of traits a lord can have.
7) Spell/ability Adjustments: Basically, there are certain spells that are OP if brought on multiple casters (specifically nets, constant AoE drain effects, summons, and healing). These classes of abilities/spells should either be nerfed insofar as to make brining 3 casters/units with said spells/abilities not OP or else such abilities/spells should be specifically limited insofar as to prevent 3 casters from using them at the same time (something like all spells/abilities of a type share a global cooldown). The first would be preferable, as it would truly balance the spells in question, but the second might be easier to implement overall.
These suggestions are pretty abbreviated due to previous discussions on them, but these are the biggest mechanics in need of adjustments for both SP and MP (at least that I've noticed: let me know if I missed something).