diff --git a/data/battle_scripts_1.s b/data/battle_scripts_1.s
index d807f5610..964a6d8a3 100644
--- a/data/battle_scripts_1.s
+++ b/data/battle_scripts_1.s
@@ -7032,6 +7032,50 @@ BattleScript_SeedSowerActivates::
 	call BattleScript_TerrainSeedLoop
 	return
 
+BattleScript_AngerShellActivates::
+	call BattleScript_AbilityPopUp
+	jumpifstat BS_TARGET, CMP_LESS_THAN, STAT_ATK, MAX_STAT_STAGE, BattleScript_AngerShellTryDef
+	jumpifstat BS_TARGET, CMP_LESS_THAN, STAT_SPATK, MAX_STAT_STAGE, BattleScript_AngerShellTryDef
+	jumpifstat BS_TARGET, CMP_LESS_THAN, STAT_SPEED, MAX_STAT_STAGE, BattleScript_AngerShellTryDef
+	jumpifstat BS_TARGET, CMP_GREATER_THAN, STAT_DEF, MIN_STAT_STAGE, BattleScript_AngerShellTryDef
+	jumpifstat BS_TARGET, CMP_EQUAL, STAT_SPDEF, MIN_STAT_STAGE, BattleScript_ButItFailed
+BattleScript_AngerShellTryDef::
+	setbyte sSTAT_ANIM_PLAYED, FALSE
+	playstatchangeanimation BS_TARGET, BIT_DEF | BIT_SPDEF, STAT_CHANGE_NEGATIVE | STAT_CHANGE_CANT_PREVENT
+	setstatchanger STAT_DEF, 1, TRUE
+	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_CHANGE_ALLOW_PTR | MOVE_EFFECT_CERTAIN, BattleScript_AngerShellTrySpDef
+	jumpifbyte CMP_EQUAL, cMULTISTRING_CHOOSER, B_MSG_STAT_WONT_INCREASE, BattleScript_AngerShellTrySpDef
+	printfromtable gStatUpStringIds
+	waitmessage B_WAIT_TIME_LONG
+BattleScript_AngerShellTrySpDef:
+	setstatchanger STAT_SPDEF, 1, TRUE
+	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_CHANGE_ALLOW_PTR | MOVE_EFFECT_CERTAIN, BattleScript_AngerShellTryAttack
+	jumpifbyte CMP_EQUAL, cMULTISTRING_CHOOSER, B_MSG_STAT_WONT_INCREASE, BattleScript_AngerShellTryAttack
+	printfromtable gStatUpStringIds
+	waitmessage B_WAIT_TIME_LONG
+BattleScript_AngerShellTryAttack:
+	setbyte sSTAT_ANIM_PLAYED, FALSE
+	playstatchangeanimation BS_TARGET, BIT_SPATK | BIT_ATK | BIT_SPEED, STAT_CHANGE_BY_TWO
+	setstatchanger STAT_ATK, 1, FALSE
+	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_CHANGE_ALLOW_PTR, BattleScript_AngerShellTrySpAtk
+	jumpifbyte CMP_EQUAL, cMULTISTRING_CHOOSER, B_MSG_STAT_WONT_INCREASE, BattleScript_AngerShellTrySpAtk
+	printfromtable gStatUpStringIds
+	waitmessage B_WAIT_TIME_LONG
+BattleScript_AngerShellTrySpAtk:
+	setstatchanger STAT_SPATK, 1, FALSE
+	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_CHANGE_ALLOW_PTR, BattleScript_AngerShellTrySpeed
+	jumpifbyte CMP_EQUAL, cMULTISTRING_CHOOSER, B_MSG_STAT_WONT_INCREASE, BattleScript_AngerShellTrySpeed
+	printfromtable gStatUpStringIds
+	waitmessage B_WAIT_TIME_LONG
+BattleScript_AngerShellTrySpeed:
+	setstatchanger STAT_SPEED, 1, FALSE
+	statbuffchange MOVE_EFFECT_AFFECTS_USER | STAT_CHANGE_ALLOW_PTR, BattleScript_AngerShellRet
+	jumpifbyte CMP_EQUAL, cMULTISTRING_CHOOSER, B_MSG_STAT_WONT_INCREASE, BattleScript_AngerShellRet
+	printfromtable gStatUpStringIds
+	waitmessage B_WAIT_TIME_LONG
+BattleScript_AngerShellRet:
+	return
+
 BattleScript_PerishSongCountGoesDown::
 	printstring STRINGID_PKMNPERISHCOUNTFELL
 	waitmessage B_WAIT_TIME_LONG
diff --git a/include/battle.h b/include/battle.h
index ebc8be057..14037b72c 100644
--- a/include/battle.h
+++ b/include/battle.h
@@ -652,6 +652,7 @@ struct BattleStruct
     u8 attackerBeforeBounce:2;
     u8 targetsDone[MAX_BATTLERS_COUNT]; // Each battler as a bit.
     u16 overwrittenAbilities[MAX_BATTLERS_COUNT];    // abilities overwritten during battle (keep separate from battle history in case of switching)
+    bool8 endturnAbilityDone[PARTY_SIZE][2]; // For some reason, adding a switchInAbilityDone equivalent in SpecialStatus didn't work.
 };
 
 #define F_DYNAMIC_TYPE_1 (1 << 6)
diff --git a/include/battle_scripts.h b/include/battle_scripts.h
index d9dafe5df..462da38db 100644
--- a/include/battle_scripts.h
+++ b/include/battle_scripts.h
@@ -434,6 +434,7 @@ extern const u8 BattleScript_MultiHitPrintStrings[];
 extern const u8 BattleScript_BurnUpRemoveType[];
 extern const u8 BattleScript_TargetAbilityStatRaiseRet[];
 extern const u8 BattleScript_SeedSowerActivates[];
+extern const u8 BattleScript_AngerShellActivates[];
 
 // zmoves
 extern const u8 BattleScript_ZMoveActivateDamaging[];
diff --git a/src/battle_util.c b/src/battle_util.c
index d3275be0d..ed425dd49 100644
--- a/src/battle_util.c
+++ b/src/battle_util.c
@@ -5749,6 +5749,20 @@ u8 AbilityBattleEffects(u8 caseID, u8 battler, u16 ability, u8 special, u16 move
                 effect++;
             }
             break;
+        case ABILITY_ANGER_SHELL:
+            if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
+             && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
+             && TARGET_TURN_DAMAGED
+             && (gBattleMons[gBattlerTarget].hp <= gBattleMons[gBattlerTarget].maxHP / 2)
+             && !gBattleStruct->endturnAbilityDone[gBattlerPartyIndexes[gBattlerTarget]][GetBattlerSide(gBattlerTarget)])
+            {
+                gBattleStruct->endturnAbilityDone[gBattlerPartyIndexes[gBattlerTarget]][GetBattlerSide(gBattlerTarget)] = TRUE;
+                gBattlerAttacker = gBattlerTarget;
+                BattleScriptPushCursor();
+                gBattlescriptCurrInstr = BattleScript_AngerShellActivates;
+                effect++;
+            }
+            break;
         }
         break;
     case ABILITYEFFECT_MOVE_END_ATTACKER: // Same as above, but for attacker