It is Wasp. She was using a formula given to her by Hank previously, to grow to giant size. Little did she know, that when Hank gave her the formula, he was not her husband but a Skrull, who had tampered with it, causing her to explode as a last ditch attack in a losing battle with the human race…..I’m not making this shit up. Talk to Bendis if it sounds stupid.