diff --git a/common/ruletypes.h b/common/ruletypes.h
index f8697f6c3..776e1d752 100644
--- a/common/ruletypes.h
+++ b/common/ruletypes.h
@@ -473,6 +473,7 @@ RULE_BOOL(Spells, UseLegacyFizzleCode, false, "Enable will turn on the legacy fi
 RULE_BOOL(Spells, LegacyManaburn, false, "Enable to have the legacy manaburn system from 2003 and earlier.")
 RULE_BOOL(Spells, EvacClearAggroInSameZone, false, "Enable to clear aggro on clients when evacing in same zone.")
 RULE_BOOL(Spells, CharmAggroOverLevel, false, "Enabling this rule will cause Charm casts over level to show resisted and cause aggro. Early EQ style.")
+RULE_BOOL(Spells, RequireMnemonicRetention, true, "Enabling will require spell slots 9-12 to have the appropriate Mnemonic Retention AA learned.")
 RULE_CATEGORY_END()
 
 RULE_CATEGORY(Combat)
diff --git a/zone/client_packet.cpp b/zone/client_packet.cpp
index e9e042ba9..e6daf6e83 100644
--- a/zone/client_packet.cpp
+++ b/zone/client_packet.cpp
@@ -4329,6 +4329,14 @@ void Client::Handle_OP_CastSpell(const EQApplicationPacket *app)
 	LogSpells("OP CastSpell: slot [{}] spell [{}] target [{}] inv [{}]", castspell->slot, castspell->spell_id, castspell->target_id, (unsigned long)castspell->inventoryslot);
 	CastingSlot slot = static_cast<CastingSlot>(castspell->slot);
 
+	if (RuleB(Spells, RequireMnemonicRetention)) {
+		if (EQ::ValueWithin(castspell->slot, 8, 11) && GetAA(aaMnemonicRetention) < (castspell->slot - 7)) {
+			InterruptSpell(castspell->spell_id);
+			Message(Chat::Red, "You do not have the required AA to use this spell slot.");
+			return;
+		}
+	}
+
 	/* Memorized Spell */
 	if (m_pp.mem_spells[castspell->slot] && m_pp.mem_spells[castspell->slot] == castspell->spell_id) {
 		uint16 spell_to_cast = 0;