Captain America attended the meeting of the Galactic Council where he suggested it was time for a Hail Mary Pass, something the Builders would never expect. J'son agreed with Rogers but decided that pass would include the help of Thanos and his Black Order. At first Steve was against allying with the mad Titan, but as things were not going their way, he went along with the plan.
Rogers contacted his fellow Illuminati members to find out if anything was going on at home as he had a bad feeling about something. Captain America confronted Thanos about not trusting him as Rogers believed even though the Council might have forgot what kind of person Thanos was he would never forget and after the war he said he would make sure Thanos pays for his crimes. They were interrupted by Danvers who relayed that since the reemergence of Captain Universe, the Builders were making their Aleph units to self-destruct in order to retreat.
Thanos came up with the idea of sending a small strike-force aboard the main Builder vessel in order to attack them before they got the chance to regroup. Rogers was part of the team who was teleported to the main Builder ship by Manifold. As they took on the Builders, Captain America's attention was drwan away from the battle as he tried to figure out what the titan was up to when he disappeared. Thor yelled at Captain America about keeping his head in the game since Rogers was focused on Thanos.
Rogers ended up following Thanos to the command deck where he learned the entire reason Thanos helped in the war to protect Earth, he wanted to kill his son Thane who was recruited by the Builders to become a successor to their plans. This provoked Captain America into a final battle against Thanos but Thanos proved to be too strong and eliminated everyone on the bridge including Rogers.