Final answer:
Pemphigus vulgaris is the autoimmune disease that causes severe skin blistering due to the epidermal layer loss in attachment to the basement membrane.
Step-by-step explanation:
The autoimmune disease that causes severe skin blistering due to the epidermal layer loss in attachment to the basement membrane is Pemphigus vulgaris. In this condition, the immune system mistakenly attacks the proteins that hold the epidermal cells together, leading to the formation of blisters. These blisters can be painful and can occur in various parts of the body, including the skin and mucous membranes.