Sentry opens without hesitation, molecular disassembly radiating from his hands in cascading waves that tear apart matter at the subatomic level. The effect washes over Superman's cells, degrading them, and for the first time in the fight Clark feels it — not pain exactly, but erosion, a structural wearing-down that his invulnerability can only partially absorb. He answers with sustained heat vision, twin beams burning at intensities that would reduce continents to slag, forcing Sentry back through sheer thermal pressure. The Void bleeds into the space around them, darkening the air, sending tendrils of entropic force into Superman's body. Clark takes every bit of it. He keeps walking forward. Sentry pours more in. Superman's cells regenerate on solar reserves so deep they read as bottomless, and he responds with Environmental Attack — hurling mass, redirecting force, using the physical world as amplifier — while Sentry burns hotter and hotter, Void aspect expanding until it starts consuming Sentry's own coherence from the inside.
That internal cost is the seam. Molecular disassembly at the scale Sentry deploys it demands constant psychic and biological output; the Void, once invoked fully, does not discriminate cleanly between target and host. Each nova-level pulse Sentry releases leaves him fractionally less stable, his regeneration cycling faster just to keep his own form intact. Superman's invulnerability, rated higher precisely because it is passive and constant rather than active and effortful, means he is simply losing less per exchange. His psychic shielding holds against the psychological turbulence rolling off the Void. He absorbs a full molecular disassembly burst that would dissolve anyone without his solar-reinforced cellular density, shakes it clear, and drives back in with brute strength at a level that matches Sentry blow for devastating blow, not to win any single exchange, but to keep the meter running.
Forty brutal minutes in, both fighters are marked — Superman's suit gone, his skin carrying the lattice-scorch of a hundred molecular strikes; Sentry's form flickering, the Void churning chaotically around him as his body fights to maintain cohesion against its own released entropy. But Superman's solar reserves are still feeding him. He can still generate heat vision at full intensity. He can still press the environmental attack, still grapple, still strike with the full weight of a being who hasn't hit a ceiling yet. Sentry's output, by contrast, begins to stutter — not gone, not broken, but the gap between each burst growing by fractions of a second, the regeneration lagging a half-beat behind the damage accumulating inside him. Superman is still going. That is the difference, and it is enough.
WINNER: Superman REASON: Superman's passive, solar-sustained invulnerability outlasts Sentry's volatile, self-consuming power output across a prolonged exchange where neither fighter can deliver a finishing blow.