Is it possible to burrow units to avoid damage from Psionic Storm?
If there was a Psionic Storm placed down over Zerg units, could you burrow them to avoid damage? If not, do they have any kind of reduced damage for being underground?
Solution 1:
Burrowed zerg units take full damage from all sources, as burrowing only hides the unit from sight.
This includes damage from AoE abilities, like Psionic Storm or enemy Infestors' fungal growth, which don't require a target (though you probably don't want to waste energy unless you're sure something is hidden there).