diff --git a/libs/blocks/merch/merch.css b/libs/blocks/merch/merch.css
index b129034c6db..ede2d35e176 100644
--- a/libs/blocks/merch/merch.css
+++ b/libs/blocks/merch/merch.css
@@ -7,7 +7,9 @@ span[data-wcs-osi] {
   display: inline-block;
 }
 
-span.placeholder-resolved[data-template="strikethrough"], span.price.price-strikethrough {
+span.placeholder-resolved[data-template="strikethrough"],
+span.price.price-strikethrough,
+span.price.price-promo-strikethrough {
   text-decoration: line-through;
 }
 
diff --git a/libs/blocks/merch/merch.js b/libs/blocks/merch/merch.js
index 9285adc92d9..7e6d270789c 100644
--- a/libs/blocks/merch/merch.js
+++ b/libs/blocks/merch/merch.js
@@ -22,6 +22,7 @@ export const PRICE_TEMPLATE_DISCOUNT = 'discount';
 export const PRICE_TEMPLATE_OPTICAL = 'optical';
 export const PRICE_TEMPLATE_REGULAR = 'price';
 export const PRICE_TEMPLATE_STRIKETHROUGH = 'strikethrough';
+export const PRICE_TEMPLATE_PROMO_STRIKETHROUGH = 'promo-strikethrough';
 export const PRICE_TEMPLATE_ANNUAL = 'annual';
 export const PRICE_TEMPLATE_LEGAL = 'legal';
 
@@ -35,6 +36,7 @@ const PRICE_TEMPLATE_MAPPING = new Map([
   ['priceAnnual', PRICE_TEMPLATE_ANNUAL],
   [PRICE_TEMPLATE_ANNUAL, PRICE_TEMPLATE_ANNUAL],
   [PRICE_TEMPLATE_LEGAL, PRICE_TEMPLATE_LEGAL],
+  [PRICE_TEMPLATE_PROMO_STRIKETHROUGH, PRICE_TEMPLATE_PROMO_STRIKETHROUGH],
 ]);
 
 export const PLACEHOLDER_KEY_DOWNLOAD = 'download';
diff --git a/libs/blocks/ost/ost.js b/libs/blocks/ost/ost.js
index 9121fdc29f6..b120b1379d8 100644
--- a/libs/blocks/ost/ost.js
+++ b/libs/blocks/ost/ost.js
@@ -8,8 +8,8 @@ const IMS_COMMERCE_CLIENT_ID = 'aos_milo_commerce';
 const IMS_SCOPE = 'AdobeID,openid';
 const IMS_ENV = 'prod';
 const IMS_PROD_URL = 'https://auth.services.adobe.com/imslib/imslib.min.js';
-const OST_SCRIPT_URL = 'https://mas.adobe.com/studio/ost/index.js';
-const OST_STYLE_URL = 'https://mas.adobe.com/studio/ost/index.css';
+const OST_SCRIPT_URL = '/studio/ost/index.js';
+const OST_STYLE_URL = '/studio/ost/index.css';
 /** @see https://git.corp.adobe.com/PandoraUI/core/blob/master/packages/react-env-provider/src/component.tsx#L49 */
 export const WCS_ENV = 'PROD';
 export const WCS_API_KEY = 'wcms-commerce-ims-ro-user-cc';
@@ -39,6 +39,38 @@ const updateParams = (params, key, value) => {
 
 document.body.classList.add('tool', 'tool-ost');
 
+/**
+ * Gets the base URL for loading Tacocat OST build file based on maslibs parameter
+ * @returns {string} Base URL for OST index.js
+ */
+export function getMasLibsBase(windowObj) {
+  const urlParams = new URLSearchParams(windowObj.location.search);
+  const masLibs = urlParams.get('maslibs');
+
+  if (!masLibs || masLibs.trim() === '') return 'https://mas.adobe.com';
+
+  const sanitizedMasLibs = masLibs.trim().toLowerCase();
+
+  if (sanitizedMasLibs === 'local') {
+    return 'http://localhost:3030';
+  }
+  if (sanitizedMasLibs === 'main') {
+    return 'https://mas.adobe.com';
+  }
+
+  // Detect current domain extension (.page or .live)
+  const { hostname } = windowObj.location;
+  const extension = hostname.endsWith('.page') ? 'page' : 'live';
+
+  if (sanitizedMasLibs.includes('--mas--')) {
+    return `https://${sanitizedMasLibs}.aem.${extension}`;
+  }
+  if (sanitizedMasLibs.includes('--')) {
+    return `https://${sanitizedMasLibs}.aem.${extension}`;
+  }
+  return `https://${sanitizedMasLibs}--mas--adobecom.aem.${extension}`;
+}
+
 /**
  * @param {Commerce.Defaults} defaults
  */
@@ -268,12 +300,12 @@ export async function loadOstEnv() {
 export default async function init(el) {
   el.innerHTML = '<div />';
 
-  loadStyle(OST_STYLE_URL);
+  loadStyle(`${getMasLibsBase(window)}${OST_STYLE_URL}`);
   loadStyle('https://use.typekit.net/pps7abe.css');
 
   const [ostEnv] = await Promise.all([
     loadOstEnv(),
-    loadScript(OST_SCRIPT_URL),
+    loadScript(`${getMasLibsBase(window)}${OST_SCRIPT_URL}`),
   ]);
 
   function openOst() {
diff --git a/test/blocks/ost/ost.test.html.js b/test/blocks/ost/ost.test.html.js
index cfe743f9d81..cf5f487b029 100644
--- a/test/blocks/ost/ost.test.html.js
+++ b/test/blocks/ost/ost.test.html.js
@@ -1,7 +1,7 @@
 import { expect } from '@esm-bundle/chai';
 
 import { mockOstDeps, unmockOstDeps } from './mocks/ost-utils.js';
-import { DEFAULT_CTA_TEXT, createLinkMarkup } from '../../../libs/blocks/ost/ost.js';
+import { DEFAULT_CTA_TEXT, createLinkMarkup, getMasLibsBase } from '../../../libs/blocks/ost/ost.js';
 
 const perpM2M = {
   offer_id: 'aeb0bf53517d46e89a1b039f859cf573',
@@ -306,3 +306,28 @@ describe('OST: merch link creation', () => {
     });
   });
 });
+describe('OST: getMasLibsBase', () => {
+  it('test different mas libs bases', () => {
+    const windowObj = {
+      location: {
+        search: '?maslibs=TEST',
+        hostname: 'main--milo--adobecom.aem.page',
+      },
+    };
+    expect(getMasLibsBase(windowObj)).to.equal('https://test--mas--adobecom.aem.page');
+    windowObj.location.search = null;
+    expect(getMasLibsBase(windowObj)).to.equal('https://mas.adobe.com');
+    windowObj.location.search = '?maslibs=local';
+    expect(getMasLibsBase(windowObj)).to.equal('http://localhost:3030');
+    windowObj.location.search = '?maslibs=main';
+    expect(getMasLibsBase(windowObj)).to.equal('https://mas.adobe.com');
+    windowObj.location.search = '?maslibs=TEST--mas--adobecom';
+    expect(getMasLibsBase(windowObj)).to.equal('https://test--mas--adobecom.aem.page');
+    windowObj.location.search = '?maslibs=TEST--sam--adobecom';
+    expect(getMasLibsBase(windowObj)).to.equal('https://test--sam--adobecom.aem.page');
+    windowObj.location.search = '?maslibs=TEST--mas--user1';
+    expect(getMasLibsBase(windowObj)).to.equal('https://test--mas--user1.aem.page');
+    windowObj.location.search = '?maslibs=TEST--sam--user1';
+    expect(getMasLibsBase(windowObj)).to.equal('https://test--sam--user1.aem.page');
+  });
+});