Nostalrius Begins - Quality wow vanilla realm (1.12)

is it suppose to get agro from mobs even before the first damage comes from blizzard? The mob moves like 4-5 yards, then the blizzard touches them.

No.
It's also not supposed to ignore LoS and it's also supposed to unstealth units even when there didn't go any dmg off.

But yes that's how it is.