Hey there! I'd like to give some thoughts on how to change the battlefields use of monsters and perhaps make the monsters that are bad a little better and the ones that break the game a little worse.
Any land monster that has 66 Speed or above with a small hitbox should never go above these values: 70 Speed, 80 Armour and 40 Melee Defence and 6500 Hp.
And should in the Roster have no other way to heal then by using of the winds of magic pool to heal. (atleast the healing effects should be drasiticly reduced by any other form or shape then magic)
Its exactly these monsters that are fast and with their small hitboxes that screw up the internal balance between the factions because if you dont have the tools in the roster to stop them you can never lock them down and kill them.
Now for the other monsters the grindy ones like the hydra, mammoth or hellpit just to name some who are also slow. You can give these between 70-100 armour depending on the HP pool. The higher the Hp pool the lower the armour. This is why the Spider has always felt like its a balanced unit because it has a low hp pool with high armour. (even though it is slightly to expensive)
Their melee defence should be around 35-40 Always never lower or higher simply because when its too low it dies to fast in the grind and when its too high it becomes difficult to deal with outside of ranged units or dedicated monster killing single entities.
I have not added the skaven bells into this simply because they are mostly wierd because of their attack animations helping them dodge ranged attacks.