From 707d8a137930b22de7570facbdb8f0825b6a1d00 Mon Sep 17 00:00:00 2001
From: KPhoenix <ericjrobinson@live.com>
Date: Wed, 5 Jan 2022 08:39:40 -0500
Subject: [PATCH] Mana Shield 1.07 bugfix revision

This is a bugfix for the vanilla 1.06 and earlier Mana Shield logic. In 1.07 Blizzard North "fixed" the Mana Shield logic since the damage reduction would decrease in effectiveness with increased spell level instead of increase. As a fix, they set the damage reduction to a flat value regardless of spell level. Originally, damage reduction started at 1/3 and capped at 1/21 at spell level 7. This fix reverses the order and gives 1/21 damage reduction at spell level 1, and caps at 1/3 damage reduction at spell level 7.
---
 Source/player.cpp | 10 ++++++++--
 Source/player.h   |  7 +++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/Source/player.cpp b/Source/player.cpp
index 68a89ea20..7a006c603 100644
--- a/Source/player.cpp
+++ b/Source/player.cpp
@@ -2104,6 +2104,12 @@ void Player::Reset()
 	*this = std::move(*emptyPlayer);
 }
 
+int Player::GetManaShieldDamageReduction()
+{
+	constexpr int8_t Max = 7;
+	return 24 - std::min(_pSplLvl[SPL_MANASHIELD], Max) * 3;
+}
+
 void Player::RestorePartialLife()
 {
 	int wholeHitpoints = _pMaxHP >> 6;
@@ -3229,7 +3235,7 @@ void ApplyPlrDamage(int pnum, int dam, int minHP /*= 0*/, int frac /*= 0*/, int
 	if (totalDamage > 0 && player.pManaShield) {
 		int8_t manaShieldLevel = player._pSplLvl[SPL_MANASHIELD];
 		if (manaShieldLevel > 0) {
-			totalDamage += totalDamage / -3;
+			totalDamage += totalDamage / -player.GetManaShieldDamageReduction();
 		}
 		if (pnum == MyPlayerId)
 			drawmanaflag = true;
@@ -3240,7 +3246,7 @@ void ApplyPlrDamage(int pnum, int dam, int minHP /*= 0*/, int frac /*= 0*/, int
 		} else {
 			totalDamage -= player._pMana;
 			if (manaShieldLevel > 0) {
-				totalDamage += totalDamage / 2;
+				totalDamage += totalDamage / (player.GetManaShieldDamageReduction() - 1);
 			}
 			player._pMana = 0;
 			player._pManaBase = player._pMaxManaBase - player._pMaxMana;
diff --git a/Source/player.h b/Source/player.h
index 9c97ba68c..bbe6c3650 100644
--- a/Source/player.h
+++ b/Source/player.h
@@ -527,6 +527,13 @@ struct Player {
 		return blkper;
 	}
 
+	/**
+	 * @brief Return reciprocal of the factor for calculating damage reduction due to Mana Shield.
+	 *
+	 * Valid only for players with Mana Shield spell level greater than zero.
+	 */
+	int GetManaShieldDamageReduction();
+
 	/**
 	 * @brief Return monster armor value after including player's armor piercing % (hellfire only)
 	 * @param monsterArmor - monster armor before applying % armor pierce