Corrected battle_calc_cardfix (magic) (#8727)

Fixed #8726

src/map/battle.cpp

@@ -737,7 +737,36 @@ int battle_calc_cardfix(int attack_type, struct block_list *src, struct block_li
 			// Affected by attacker ATK bonuses
 			if( sd && !nk[NK_IGNOREATKCARD] ) {
 				int32 race2_val = 0;
+#ifdef RENEWAL
+
+// Simplified formula to round down the damage
+#define APPLY_CARDFIX_RE(damage, fix) { (damage) = (damage) - (int64)(((damage) * (100 - max(0, 100+(fix)))) / 100); }
+				// On (at least) BF_MAGIC, damages are calculated consecutively and rounded down in the following order to match official damage :
+				// size, race2, ele, atk_ele, race, class
+				APPLY_CARDFIX_RE( damage, sd->indexed_bonus.magic_addsize[tstatus->size] + sd->indexed_bonus.magic_addsize[SZ_ALL] );
 
+				// race2 is the same as the bonus per class ID
+				for (const auto &raceit : t_race2)
+					race2_val += sd->indexed_bonus.magic_addrace2[raceit];
+				for (const auto &it : sd->add_mdmg) {
+					if (it.id == t_class) {
+						race2_val += it.val;
+						break;
+					}
+				}
+				APPLY_CARDFIX_RE( damage, race2_val );
+
+				if( !nk[NK_IGNOREELEMENT] ) { // Affected by Element modifier bonuses
+					APPLY_CARDFIX_RE( damage, sd->indexed_bonus.magic_addele[tstatus->def_ele] + sd->indexed_bonus.magic_addele[ELE_ALL] +
+						sd->indexed_bonus.magic_addele_script[tstatus->def_ele] + sd->indexed_bonus.magic_addele_script[ELE_ALL] );
+					APPLY_CARDFIX_RE( damage, sd->indexed_bonus.magic_atk_ele[rh_ele] + sd->indexed_bonus.magic_atk_ele[ELE_ALL] );
+				}
+				APPLY_CARDFIX_RE( damage, sd->indexed_bonus.magic_addrace[tstatus->race] + sd->indexed_bonus.magic_addrace[RC_ALL] );
+				APPLY_CARDFIX_RE( damage, sd->indexed_bonus.magic_addclass[tstatus->class_] + sd->indexed_bonus.magic_addclass[CLASS_ALL] );
+#undef APPLY_CARDFIX_RE
+
+// Pre-renewal / old renewal behaviour
+#else
 				for (const auto &raceit : t_race2)
 					race2_val += sd->indexed_bonus.magic_addrace2[raceit];
 				cardfix = cardfix * (100 + sd->indexed_bonus.magic_addrace[tstatus->race] + sd->indexed_bonus.magic_addrace[RC_ALL] + race2_val) / 100;
@@ -755,6 +784,7 @@ int battle_calc_cardfix(int attack_type, struct block_list *src, struct block_li
 					}
 				}
 				APPLY_CARDFIX(damage, cardfix);
+#endif
 			}
 
 			// Affected by target DEF bonuses