@kirk1898 Phainon's ultimate is definitely a Reality Marble, since only him and his targets can exist and does not allow for outside interference.
It really depends on which Ea you are referencing, as their are multiple versions. In the original FSN, he holds back while using and at his full power, it is still blocked by Avalon. In Strange Fake, it tore through a Reality Marble, and nearly destroyed the world when he used it at full power while in the real world. In fate/Kalaid, it is severely nerfed thanks to his child form and half of his power being sealed in the card.