Disclaimer: EXTREME spoilers for "The Sacrifice" questline for Warframe.

Excalibur Umbra, on the brink of death. Surrounded by Sentients and his creator. Somehow escapes Ballas' clutches, one attack away, on his final deathbed, deathrow even if all had gone by his creator's plan. A flash of light akin to him drawing his exalted blade flashes, and any trace of him is gone.