Some questions

So I was raiding the other day and saw this happen - I had two yellow, I think, heroes and one of them was blinded. I threw yellow tiles and some missed. Since the other yellow was not blinded, his hit chance should be 100% and no tiles should ever miss and deal 0 damage.
So when you color stack heroes, how is tile damage, hit/miss or critical chance calculated?
Is it calculated per hero and then added? Doesnt seem to be the case with the above example.
Do they then add same color heroes’ attacks and treat it as a single tile with that attack?
What about hit and crit chance? Do they randomly pick a hero and apply his hit/crit chance, as I saw mentioned somewhere? Do they average it across heroes and use that average for the combined tile? Or do they do a weighted average which would be more proper? (for ab extreme example, you have 1 hero with 1 attack and 0% hit chance and the other hero with 100 attack and 100% hit chance. If you do it properly, average damage per hit will be 100, but if you average the hit chance, it will be roughly half that).

Every tile would have 1/n° chance to use one or another hero’s troop.
The attack would be the sum of the same-color heroes’ attacks (with a chance to miss if blinded) and the crit would be borrowed from the just one hero, so no 100% crit chance.