vcmi: 100% damage reduction is damage immunity

lib/CCreatureHandler.cpp

@@ -1178,8 +1178,9 @@ void CCreatureHandler::loadStackExp(Bonus & b, BonusList & bl, CLegacyConfigPars
 				b.subtype = 1; //not positive
 				break;
 			case 'O':
-				b.type = BonusType::FIRE_IMMUNITY;
-				b.subtype = 2; //only direct damage
+				b.type = BonusType::SPELL_DAMAGE_REDUCTION;
+				b.subtype = 1; //Fire school
+				b.val = 100; //Full damage immunity
 				break;
 			case 'f':
 				b.type = BonusType::FIRE_IMMUNITY;
@@ -1190,31 +1191,36 @@ void CCreatureHandler::loadStackExp(Bonus & b, BonusList & bl, CLegacyConfigPars
 				b.subtype = 1; //not positive
 				break;
 			case 'W':
-				b.type = BonusType::WATER_IMMUNITY;
-				b.subtype = 2; //only direct damage
+				b.type = BonusType::SPELL_DAMAGE_REDUCTION;
+				b.subtype = 2; //Water school
+				b.val = 100; //Full damage immunity
 				break;
 			case 'w':
 				b.type = BonusType::WATER_IMMUNITY;
 				b.subtype = 0; //all
 				break;
 			case 'E':
-				b.type = BonusType::EARTH_IMMUNITY;
-				b.subtype = 2; //only direct damage
+				b.type = BonusType::SPELL_DAMAGE_REDUCTION;
+				b.subtype = 3; //Earth school
+				b.val = 100; //Full damage immunity
 				break;
 			case 'e':
 				b.type = BonusType::EARTH_IMMUNITY;
 				b.subtype = 0; //all
 				break;
 			case 'A':
-				b.type = BonusType::AIR_IMMUNITY;
-				b.subtype = 2; //only direct damage
+				b.type = BonusType::SPELL_DAMAGE_REDUCTION;
+				b.subtype = 0; //Air school
+				b.val = 100; //Full damage immunity
 				break;
 			case 'a':
 				b.type = BonusType::AIR_IMMUNITY;
 				b.subtype = 0; //all
 				break;
 			case 'D':
-				b.type = BonusType::DIRECT_DAMAGE_IMMUNITY;
+				b.type = BonusType::SPELL_DAMAGE_REDUCTION;
+				b.subtype = -1; //all
+				b.val = 100; //Full damage immunity
 				break;
 			case '0':
 				b.type = BonusType::RECEPTIVE;

lib/spells/effects/Damage.cpp

@@ -11,6 +11,7 @@
 
 #include "Damage.h"
 #include "Registry.h"
+#include "../CSpellHandler.h"
 #include "../ISpellMechanics.h"
 
 #include "../../NetPacks.h"
@@ -20,6 +21,8 @@
 #include "../../CGeneralTextHandler.h"
 #include "../../serializer/JsonSerializeFormat.h"
 
+#include <vcmi/spells/Spell.h>
+
 VCMI_LIB_NAMESPACE_BEGIN
 
 namespace spells
@@ -82,16 +85,14 @@ bool Damage::isReceptive(const Mechanics * m, const battle::Unit * unit) const
 	if(!UnitEffect::isReceptive(m, unit))
 		return false;
 
+	bool isImmune = m->getSpell()->isMagical() && (unit->getBonusBearer()->valOfBonuses(BonusType::SPELL_DAMAGE_REDUCTION, -1) >= 100); //General spell damage immunity
 	//elemental immunity for damage
-	auto filter = m->getElementalImmunity();
-
-	for(auto element : filter)
+	m->getSpell()->forEachSchool([&](const SchoolInfo & cnf, bool & stop)
 	{
-		if(!m->isPositiveSpell() && unit->hasBonusOfType(element, 2))
-			return false;
-	}
+		isImmune |= (unit->getBonusBearer()->valOfBonuses(BonusType::SPELL_DAMAGE_REDUCTION, static_cast<ui8>(cnf.id)) >= 100); //100% reduction is immunity
+	});
 
-	return true;
+	return !isImmune;
 }
 
 void Damage::serializeJsonUnitEffect(JsonSerializeFormat & handler)