The chronurgy wizard in our group met a former research partner of his, who had gone mad after seeing both the beginning and end of time. He offered to share this knowledge with the wizard if he killed the rest of us. The session ended there though since wizard needed to leave.

The wizard joining up with his former partner turned out to be a smooth way for the wizard player to bow out of the campaign though, so it's not all bad.

Searing Vengeance, Level 14 Celestial Warlock Feature

Starting at 14th level, the radiant energy you channel allows you to resist death. When you have to make a death saving throw at the start of your turn, you can instead spring back to your feet with a burst of radiant energy. You regain hit points equal to half your hit point maximum, and then you stand up if you so choose. Each creature of your choice that is within 30 feet of you takes radiant damage equal to 2d8 + your Charisma modifier, and is blinded until the end of the current turn. Once you use this feature, you can’t use it again until you finish a long rest