curl --request GET \
  --url https://{cluster}.voucherify.io/v1/promotions/{campaignId}/tiers \
  --header 'Authorization: Bearer <token>' \
  --header 'X-App-Id: <api-key>' \
  --header 'X-App-Token: <api-key>'

{
  "object": "list",
  "data_ref": "tiers",
  "tiers": [
    {
      "id": "promo_xyOKjAmysZrwt3aqq1dMUwMU",
      "created_at": "2022-04-07T08:43:53.730Z",
      "updated_at": "2022-08-26T05:22:43.220Z",
      "name": "Amount",
      "banner": "Get $10 off entire order",
      "action": {
        "discount": {
          "type": "AMOUNT",
          "amount_off": 1000,
          "effect": "APPLY_TO_ORDER"
        }
      },
      "metadata": {},
      "hierarchy": 2,
      "promotion_id": "camp_SGq39XXJ47vm7Xys3D0NLgQ0",
      "campaign": {
        "id": "camp_SGq39XXJ47vm7Xys3D0NLgQ0",
        "start_date": null,
        "expiration_date": null,
        "active": true,
        "category_id": "cat_0b5f67863083bf7c05",
        "object": "campaign"
      },
      "campaign_id": "camp_SGq39XXJ47vm7Xys3D0NLgQ0",
      "active": true,
      "summary": {
        "redemptions": {
          "total_redeemed": 1
        },
        "orders": {
          "total_amount": 2187,
          "total_discount_amount": 1000
        }
      },
      "object": "promotion_tier",
      "validation_rule_assignments": null
    },
    {
      "id": "promo_CQonGnrsFAdEJfJQ3oKB3a8G",
      "created_at": "2022-04-07T08:43:53.581Z",
      "updated_at": "2022-08-26T05:22:43.008Z",
      "name": "Percentage",
      "banner": "Get 10% OFF on entire order",
      "action": {
        "discount": {
          "type": "PERCENT",
          "percent_off": 10,
          "effect": "APPLY_TO_ORDER"
        }
      },
      "metadata": {},
      "hierarchy": 1,
      "promotion_id": "camp_SGq39XXJ47vm7Xys3D0NLgQ0",
      "campaign": {
        "id": "camp_SGq39XXJ47vm7Xys3D0NLgQ0",
        "start_date": null,
        "expiration_date": null,
        "active": true,
        "category_id": "cat_0b5f67863083bf7c05",
        "object": "campaign"
      },
      "campaign_id": "camp_SGq39XXJ47vm7Xys3D0NLgQ0",
      "active": true,
      "summary": {
        "redemptions": {
          "total_redeemed": 1
        },
        "orders": {
          "total_amount": 71600,
          "total_discount_amount": 7160
        }
      },
      "object": "promotion_tier",
      "validation_rule_assignments": null
    }
  ],
  "total": 2,
  "has_more": false
}