diff --git a/src/server/game/AI/SmartScripts/SmartScript.cpp b/src/server/game/AI/SmartScripts/SmartScript.cpp
index 1091f1e18..ef938d68b 100644
--- a/src/server/game/AI/SmartScripts/SmartScript.cpp
+++ b/src/server/game/AI/SmartScripts/SmartScript.cpp
@@ -3141,7 +3141,7 @@ void SmartScript::ProcessAction(SmartScriptHolder& e, Unit* unit, uint32 var0, u
                             // unless target is outside spell range, out of mana, or LOS.
 
                             bool _allowMove = false;
-                            SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(e.action.castCustom.spell);
+                            SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(e.action.castCustom.spell); // AssertSpellInfo?
                             int32 mana = me->GetPower(POWER_MANA);
 
                             if (me->GetDistance((*itr)->ToUnit()) > spellInfo->GetMaxRange(true) ||
diff --git a/src/server/game/Conditions/ConditionMgr.cpp b/src/server/game/Conditions/ConditionMgr.cpp
index ce3e015a3..a3731901a 100644
--- a/src/server/game/Conditions/ConditionMgr.cpp
+++ b/src/server/game/Conditions/ConditionMgr.cpp
@@ -1205,8 +1205,7 @@ bool ConditionMgr::addToGossipMenuItems(Condition* cond)
 bool ConditionMgr::addToSpellImplicitTargetConditions(Condition* cond)
 {
     uint32 conditionEffMask = cond->SourceGroup;
-    SpellInfo* spellInfo = const_cast<SpellInfo*>(sSpellMgr->GetSpellInfo(cond->SourceEntry));
-    ASSERT(spellInfo);
+    SpellInfo* spellInfo = const_cast<SpellInfo*>(sSpellMgr->AssertSpellInfo(cond->SourceEntry));
     std::list<uint32> sharedMasks;
     for (uint8 i = 0; i < MAX_SPELL_EFFECTS; ++i)
     {
diff --git a/src/server/game/Entities/Player/Player.cpp b/src/server/game/Entities/Player/Player.cpp
index a8abb89e1..11b068db4 100644
--- a/src/server/game/Entities/Player/Player.cpp
+++ b/src/server/game/Entities/Player/Player.cpp
@@ -4367,7 +4367,7 @@ bool Player::Has310Flyer(bool checkAllSpells, uint32 excludeSpellId)
                 if (_spell_idx->second->skillId != SKILL_MOUNTS)
                     break;  // We can break because mount spells belong only to one skillline (at least 310 flyers do)
 
-                spellInfo = sSpellMgr->GetSpellInfo(itr->first);
+                spellInfo = sSpellMgr->AssertSpellInfo(itr->first);
                 for (uint8 i = 0; i < MAX_SPELL_EFFECTS; ++i)
                     if (spellInfo->Effects[i].ApplyAuraName == SPELL_AURA_MOD_INCREASE_MOUNTED_FLIGHT_SPEED &&
                             spellInfo->Effects[i].CalcValue() == 310)
@@ -4408,9 +4408,7 @@ void Player::RemoveArenaSpellCooldowns(bool removeActivePetCooldowns)
     {
         next = itr;
         ++next;
-        SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(itr->first);
-        if (!spellInfo) // xinef: impossibru...
-            continue;
+        SpellInfo const* spellInfo = sSpellMgr->AssertSpellInfo(itr->first);
 
         if (spellInfo->HasAttribute(SPELL_ATTR4_IGNORE_DEFAULT_ARENA_RESTRICTIONS))
             RemoveSpellCooldown(itr->first, true);
@@ -22480,12 +22478,7 @@ void Player::ProhibitSpellSchool(SpellSchoolMask idSchoolMask, uint32 unTimeMs)
         if (itr->second->State == PLAYERSPELL_REMOVED)
             continue;
         uint32 unSpellId = itr->first;
-        SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(unSpellId);
-        if (!spellInfo)
-        {
-            ASSERT(spellInfo);
-            continue;
-        }
+        SpellInfo const* spellInfo = sSpellMgr->AssertSpellInfo(unSpellId);
 
         // Not send cooldown for this spells
         if (spellInfo->IsCooldownStartedOnEvent())
diff --git a/src/server/game/Spells/Auras/SpellAuraEffects.cpp b/src/server/game/Spells/Auras/SpellAuraEffects.cpp
index 4edc754d9..5a6b8aae2 100644
--- a/src/server/game/Spells/Auras/SpellAuraEffects.cpp
+++ b/src/server/game/Spells/Auras/SpellAuraEffects.cpp
@@ -5256,7 +5256,7 @@ void AuraEffect::HandleAuraDummy(AuraApplication const* aurApp, uint8 mode, bool
                             uint32 spellId = 24659;
                             if (apply && caster)
                             {
-                                SpellInfo const* spell = sSpellMgr->GetSpellInfo(spellId);
+                                SpellInfo const* spell = sSpellMgr->AssertSpellInfo(spellId);
 
                                 for (uint32 i = 0; i < spell->StackAmount; ++i)
                                     caster->CastSpell(target, spell->Id, true, nullptr, nullptr, GetCasterGUID());
@@ -5271,7 +5271,7 @@ void AuraEffect::HandleAuraDummy(AuraApplication const* aurApp, uint8 mode, bool
                             uint32 spellId = 24662;
                             if (apply && caster)
                             {
-                                SpellInfo const* spell = sSpellMgr->GetSpellInfo(spellId);
+                                SpellInfo const* spell = sSpellMgr->AssertSpellInfo(spellId);
                                 for (uint32 i = 0; i < spell->StackAmount; ++i)
                                     caster->CastSpell(target, spell->Id, true, nullptr, nullptr, GetCasterGUID());
                                 break;
diff --git a/src/server/game/Spells/SpellEffects.cpp b/src/server/game/Spells/SpellEffects.cpp
index bcddd8226..13f24bcbf 100644
--- a/src/server/game/Spells/SpellEffects.cpp
+++ b/src/server/game/Spells/SpellEffects.cpp
@@ -1997,7 +1997,7 @@ void Spell::EffectEnergize(SpellEffIndex effIndex)
             sSpellMgr->GetSetOfSpellsInSpellGroupWithFlag(1, SPELL_GROUP_SPECIAL_FLAG_ELIXIR_BATTLE, availableElixirs);
         for (std::set<uint32>::iterator itr = availableElixirs.begin(); itr != availableElixirs.end();)
         {
-            SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(*itr);
+            SpellInfo const* spellInfo = sSpellMgr->AssertSpellInfo(*itr);
             if (spellInfo->SpellLevel < m_spellInfo->SpellLevel || spellInfo->SpellLevel > unitTarget->getLevel())
                 availableElixirs.erase(itr++);
             else
diff --git a/src/server/game/Spells/SpellMgr.h b/src/server/game/Spells/SpellMgr.h
index 3017691f8..e51b2e38e 100644
--- a/src/server/game/Spells/SpellMgr.h
+++ b/src/server/game/Spells/SpellMgr.h
@@ -684,6 +684,14 @@ public:
 
     // SpellInfo object management
     [[nodiscard]] SpellInfo const* GetSpellInfo(uint32 spellId) const { return spellId < GetSpellInfoStoreSize() ?  mSpellInfoMap[spellId] : nullptr; }
+    // Use this only with 100% valid spellIds
+    SpellInfo const* AssertSpellInfo(uint32 spellId) const
+    {
+        ASSERT(spellId < GetSpellInfoStoreSize());
+        SpellInfo const* spellInfo = mSpellInfoMap[spellId];
+        ASSERT(spellInfo);
+        return spellInfo;
+    }
     [[nodiscard]] uint32 GetSpellInfoStoreSize() const { return mSpellInfoMap.size(); }
 
     // Talent Additional Set
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_blood_queen_lana_thel.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_blood_queen_lana_thel.cpp
index 7b2c7605d..5207add80 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_blood_queen_lana_thel.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_blood_queen_lana_thel.cpp
@@ -594,7 +594,7 @@ public:
         {
             if ((aurEff->GetTickNumber() % 2) == 0)
                 return;
-            SpellInfo const* damageSpell = sSpellMgr->GetSpellInfo(SPELL_PACT_OF_THE_DARKFALLEN_DAMAGE);
+            SpellInfo const* damageSpell = sSpellMgr->AssertSpellInfo(SPELL_PACT_OF_THE_DARKFALLEN_DAMAGE);
             int32 damage = damageSpell->Effects[EFFECT_0].CalcValue();
             float herobonus = ((GetTarget()->FindMap() && GetTarget()->FindMap()->IsHeroic()) ? 0.2f : 0.0f);
             float multiplier = 0.5f + herobonus + 0.1f * uint32(aurEff->GetTickNumber() / 10); // do not convert to 0.01f - we need tick number/10 as INT (damage increases every 10 ticks)
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_icecrown_gunship_battle.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_icecrown_gunship_battle.cpp
index a9de8ebcf..0fd281bac 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_icecrown_gunship_battle.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_icecrown_gunship_battle.cpp
@@ -1958,7 +1958,7 @@ public:
 
         void HandleRemove(AuraEffect const* aurEff, AuraEffectHandleModes /*mode*/)
         {
-            SpellInfo const* damageInfo = sSpellMgr->GetSpellInfo(SPELL_ROCKET_PACK_DAMAGE);
+            SpellInfo const* damageInfo = sSpellMgr->AssertSpellInfo(SPELL_ROCKET_PACK_DAMAGE);
             GetTarget()->CastCustomSpell(SPELL_ROCKET_PACK_DAMAGE, SPELLVALUE_BASE_POINT0, 2 * (damageInfo->Effects[EFFECT_0].CalcValue() + aurEff->GetTickNumber() * aurEff->GetAmplitude()), nullptr, true);
             GetTarget()->CastSpell((Unit*)nullptr, SPELL_ROCKET_BURST, true);
         }
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp
index 77f68346b..e0b4b3b38 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_professor_putricide.cpp
@@ -1197,7 +1197,7 @@ public:
                 return;
 
             uint32 triggerSpell = GetSpellInfo()->Effects[aurEff->GetEffIndex()].TriggerSpell;
-            SpellInfo const* spell = sSpellMgr->GetSpellInfo(triggerSpell);
+            SpellInfo const* spell = sSpellMgr->AssertSpellInfo(triggerSpell);
             spell = sSpellMgr->GetSpellForDifficultyFromSpell(spell, caster);
 
             int32 damage = spell->Effects[EFFECT_0].CalcValue(caster);
diff --git a/src/server/scripts/Spells/spell_dk.cpp b/src/server/scripts/Spells/spell_dk.cpp
index f5b28e7ef..ce329df5a 100644
--- a/src/server/scripts/Spells/spell_dk.cpp
+++ b/src/server/scripts/Spells/spell_dk.cpp
@@ -1171,7 +1171,7 @@ public:
 
         void CalculateAmount(AuraEffect const* /*aurEff*/, int32& amount, bool& canBeRecalculated)
         {
-            SpellInfo const* talentSpell = sSpellMgr->GetSpellInfo(SPELL_DK_ANTI_MAGIC_SHELL_TALENT);
+            SpellInfo const* talentSpell = sSpellMgr->AssertSpellInfo(SPELL_DK_ANTI_MAGIC_SHELL_TALENT);
             amount = talentSpell->Effects[EFFECT_0].CalcValue(GetCaster());
             if (Unit* totem = GetCaster())
                 if (Unit* owner = totem->ToTotem()->GetSummoner())
@@ -2563,7 +2563,7 @@ public:
         {
             // min pct of hp is stored in effect 0 of talent spell
             uint8 rank = GetSpellInfo()->GetRank();
-            SpellInfo const* talentProto = sSpellMgr->GetSpellInfo(sSpellMgr->GetSpellWithRank(SPELL_DK_WILL_OF_THE_NECROPOLIS_TALENT_R1, rank));
+            SpellInfo const* talentProto = sSpellMgr->AssertSpellInfo(sSpellMgr->GetSpellWithRank(SPELL_DK_WILL_OF_THE_NECROPOLIS_TALENT_R1, rank));
 
             int32 remainingHp = int32(GetTarget()->GetHealth() - dmgInfo.GetDamage());
             int32 minHp = int32(GetTarget()->CountPctFromMaxHealth(talentProto->Effects[EFFECT_0].CalcValue(GetCaster())));
diff --git a/src/server/scripts/Spells/spell_generic.cpp b/src/server/scripts/Spells/spell_generic.cpp
index 5533cb1af..0c894628b 100644
--- a/src/server/scripts/Spells/spell_generic.cpp
+++ b/src/server/scripts/Spells/spell_generic.cpp
@@ -3596,7 +3596,7 @@ public:
 
         void Register() override
         {
-            SpellInfo const* spell = sSpellMgr->GetSpellInfo(m_scriptSpellId);
+            SpellInfo const* spell = sSpellMgr->AssertSpellInfo(m_scriptSpellId);
 
             if (spell->HasEffect(SPELL_EFFECT_SCRIPT_EFFECT))
                 OnEffectHitTarget += SpellEffectFn(spell_gen_mounted_charge_SpellScript::HandleScriptEffect, EFFECT_FIRST_FOUND, SPELL_EFFECT_SCRIPT_EFFECT);
@@ -3669,7 +3669,7 @@ public:
 
         void Register() override
         {
-            SpellInfo const* spell = sSpellMgr->GetSpellInfo(m_scriptSpellId);
+            SpellInfo const* spell = sSpellMgr->AssertSpellInfo(m_scriptSpellId);
 
             // Defend spells cast by NPCs (add visuals)
             if (spell->Effects[EFFECT_0].ApplyAuraName == SPELL_AURA_MOD_DAMAGE_PERCENT_TAKEN)
diff --git a/src/server/scripts/Spells/spell_mage.cpp b/src/server/scripts/Spells/spell_mage.cpp
index d4ba2734d..f800b83c8 100644
--- a/src/server/scripts/Spells/spell_mage.cpp
+++ b/src/server/scripts/Spells/spell_mage.cpp
@@ -579,7 +579,7 @@ public:
             PlayerSpellMap const& spellMap = caster->GetSpellMap();
             for (PlayerSpellMap::const_iterator itr = spellMap.begin(); itr != spellMap.end(); ++itr)
             {
-                SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(itr->first);
+                SpellInfo const* spellInfo = sSpellMgr->AssertSpellInfo(itr->first);
                 if (spellInfo->SpellFamilyName == SPELLFAMILY_MAGE && (spellInfo->GetSchoolMask() & SPELL_SCHOOL_MASK_FROST) && spellInfo->Id != SPELL_MAGE_COLD_SNAP && spellInfo->GetRecoveryTime() > 0)
                 {
                     SpellCooldowns::iterator citr = caster->GetSpellCooldownMap().find(spellInfo->Id);
@@ -833,7 +833,7 @@ public:
         {
             PreventDefaultAction();
 
-            SpellInfo const* igniteDot = sSpellMgr->GetSpellInfo(SPELL_MAGE_IGNITE);
+            SpellInfo const* igniteDot = sSpellMgr->AssertSpellInfo(SPELL_MAGE_IGNITE);
             int32 pct = 8 * GetSpellInfo()->GetRank();
 
             int32 amount = int32(CalculatePct(eventInfo.GetDamageInfo()->GetDamage(), pct) / igniteDot->GetMaxTicks());
diff --git a/src/server/scripts/Spells/spell_priest.cpp b/src/server/scripts/Spells/spell_priest.cpp
index 2ea8928c6..e3dafa1e4 100644
--- a/src/server/scripts/Spells/spell_priest.cpp
+++ b/src/server/scripts/Spells/spell_priest.cpp
@@ -277,7 +277,7 @@ public:
         {
             PreventDefaultAction();
 
-            SpellInfo const* triggeredSpellInfo = sSpellMgr->GetSpellInfo(SPELL_PRIEST_GLYPH_OF_PRAYER_OF_HEALING_HEAL);
+            SpellInfo const* triggeredSpellInfo = sSpellMgr->AssertSpellInfo(SPELL_PRIEST_GLYPH_OF_PRAYER_OF_HEALING_HEAL);
             int32 heal = int32(CalculatePct(int32(eventInfo.GetHealInfo()->GetHeal()), aurEff->GetAmount()) / triggeredSpellInfo->GetMaxTicks());
             GetTarget()->CastCustomSpell(SPELL_PRIEST_GLYPH_OF_PRAYER_OF_HEALING_HEAL, SPELLVALUE_BASE_POINT0, heal, eventInfo.GetProcTarget(), true, nullptr, aurEff);
         }
diff --git a/src/server/scripts/Spells/spell_rogue.cpp b/src/server/scripts/Spells/spell_rogue.cpp
index f1a38c46a..049145c2a 100644
--- a/src/server/scripts/Spells/spell_rogue.cpp
+++ b/src/server/scripts/Spells/spell_rogue.cpp
@@ -520,7 +520,7 @@ public:
             PlayerSpellMap const& spellMap = caster->GetSpellMap();
             for (PlayerSpellMap::const_iterator itr = spellMap.begin(); itr != spellMap.end(); ++itr)
             {
-                SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(itr->first);
+                SpellInfo const* spellInfo = sSpellMgr->AssertSpellInfo(itr->first);
                 if (spellInfo->SpellFamilyName == SPELLFAMILY_ROGUE)
                 {
                     if (spellInfo->SpellFamilyFlags[1] & SPELLFAMILYFLAG1_ROGUE_COLDB_SHADOWSTEP ||      // Cold Blood, Shadowstep
diff --git a/src/server/scripts/Spells/spell_warlock.cpp b/src/server/scripts/Spells/spell_warlock.cpp
index 6020f7b09..e7aa0282e 100644
--- a/src/server/scripts/Spells/spell_warlock.cpp
+++ b/src/server/scripts/Spells/spell_warlock.cpp
@@ -629,7 +629,7 @@ public:
                             break;
                         case CREATURE_FAMILY_VOIDWALKER:
                             {
-                                SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(SPELL_WARLOCK_DEMONIC_EMPOWERMENT_VOIDWALKER);
+                                SpellInfo const* spellInfo = sSpellMgr->AssertSpellInfo(SPELL_WARLOCK_DEMONIC_EMPOWERMENT_VOIDWALKER);
                                 int32 hp = int32(targetCreature->CountPctFromMaxHealth(GetCaster()->CalculateSpellDamage(targetCreature, spellInfo, 0)));
                                 targetCreature->CastCustomSpell(targetCreature, SPELL_WARLOCK_DEMONIC_EMPOWERMENT_VOIDWALKER, &hp, nullptr, nullptr, true);
                                 //unitTarget->CastSpell(unitTarget, 54441, true);
@@ -1013,7 +1013,7 @@ public:
                 // WARLOCK_DEMONIC_CIRCLE_ALLOW_CAST; allowing him to cast the WARLOCK_DEMONIC_CIRCLE_TELEPORT.
                 // If not in range remove the WARLOCK_DEMONIC_CIRCLE_ALLOW_CAST.
 
-                SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(SPELL_WARLOCK_DEMONIC_CIRCLE_TELEPORT);
+                SpellInfo const* spellInfo = sSpellMgr->AssertSpellInfo(SPELL_WARLOCK_DEMONIC_CIRCLE_TELEPORT);
 
                 if (GetTarget()->IsWithinDist(circle, spellInfo->GetMaxRange(true)))
                 {