Does this card affect all currently damaged unit's of an opponent after combat or just those that receive damage on current turn ?

Another question is if Shrine to Nurgle affects also the units damaged by indirect damage. does the unit corrupted immediately after it damaged ?

Zavullon said:

Only those damaged in the combat.

Zavullon said:

FAQ:

"CS 98 Shrine to Nurgle
Should read: “Kingdom. Forced: When an
opponent’s unit is dealt combat damage,
corrupt that unit.”

Combat damage is damage by units in combat, either attackers or defenders. Everything else is non-combat damage and doesn't combo with StN.

I still confused. If for example i have a damaged unit from a previous turn combat. Let assume also that this unit doesn't received any additional damage from combat during current turn. Does the STN affect the damaged card and make it corrupted ?

No, Forced kicks in for each unit as it is damaged in combat. Already having damage and being in combat doesn't kick in (though said units possibly were hit by StN in the combat they received their damage).