Increase the resistance values from Stat Shards and disallow stacking
Riot admitted damage was too high and this pre-season has done almost nothing to alleviate that.
Even if you can get a somewhat meaningful amount of early resistances from the shards by stacking you're still taking Season 8 level damage from the other damage type. Meanwhile mixing both Armor and Magic Resist shards gives you such a trivial increase in durability that its hardly meaningful.