diff --git a/public/images/arenas/mountain_a.png b/public/images/arenas/mountain_a.png
index 3403e362caa..f3896fb409f 100644
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diff --git a/public/images/arenas/mountain_b.png b/public/images/arenas/mountain_b.png
index 95e4cc6267f..99b4399b1f3 100644
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diff --git a/public/images/arenas/mountain_b_1.png b/public/images/arenas/mountain_b_1.png
new file mode 100644
index 00000000000..aa7c1209f5a
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diff --git a/public/images/arenas/mountain_b_2.png b/public/images/arenas/mountain_b_2.png
new file mode 100644
index 00000000000..377c3b16b23
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diff --git a/public/images/arenas/mountain_b_3.png b/public/images/arenas/mountain_b_3.png
new file mode 100644
index 00000000000..ba44117634a
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diff --git a/public/images/arenas/mountain_bg.png b/public/images/arenas/mountain_bg.png
index 04bae47cef8..df47f054a91 100644
Binary files a/public/images/arenas/mountain_bg.png and b/public/images/arenas/mountain_bg.png differ
diff --git a/src/arena.ts b/src/arena.ts
index 66a04e1d579..04e1108581f 100644
--- a/src/arena.ts
+++ b/src/arena.ts
@@ -331,6 +331,7 @@ export function getBiomeHasProps(biomeType: Biome): boolean {
     case Biome.BEACH:
     case Biome.LAKE:
     case Biome.SEABED:
+    case Biome.MOUNTAIN:
     case Biome.BADLANDS:
     case Biome.CAVE:
     case Biome.DESERT:
diff --git a/src/battle-phases.ts b/src/battle-phases.ts
index c876ab42b1c..ab3ca3bc19c 100644
--- a/src/battle-phases.ts
+++ b/src/battle-phases.ts
@@ -242,7 +242,7 @@ export class EncounterPhase extends BattlePhase {
 
   doEncounter() {
     if (startingWave > 10) {
-      for (let m = 0; m < Math.floor(startingWave / 10); m++)
+      for (let m = 0; m < Math.min(Math.floor(startingWave / 10), 99); m++)
         this.scene.addModifier(getPlayerModifierTypeOptionsForWave((m + 1) * 10, 1, this.scene.getParty())[0].type.newModifier());
     }
 
diff --git a/src/battle-scene.ts b/src/battle-scene.ts
index 9c2d7a62555..088022ddaae 100644
--- a/src/battle-scene.ts
+++ b/src/battle-scene.ts
@@ -2,7 +2,7 @@ import Phaser from 'phaser';
 import { Biome } from './data/biome';
 import UI from './ui/ui';
 import { EncounterPhase, SummonPhase, NextEncounterPhase, NewBiomeEncounterPhase, SelectBiomePhase, MessagePhase, CheckLoadPhase, TurnInitPhase, ReturnPhase, ToggleDoublePositionPhase, CheckSwitchPhase } from './battle-phases';
-import Pokemon, { PlayerPokemon, EnemyPokemon, FieldPosition } from './pokemon';
+import Pokemon, { PlayerPokemon, EnemyPokemon } from './pokemon';
 import PokemonSpecies, { allSpecies, getPokemonSpecies, initSpecies } from './data/pokemon-species';
 import * as Utils from './utils';
 import { Modifier, ModifierBar, ConsumablePokemonModifier, ConsumableModifier, PokemonHpRestoreModifier, HealingBoosterModifier, PersistentModifier, PokemonHeldItemModifier, ModifierPredicate } from './modifier/modifier';