Aven Riftwatcher

Flying
Vanishing 3 (This creature enters the battlefield with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Aven Riftwatcher enters the battlefield or leaves the battlefield, you gain 2 life.

Calciderm

Shroud (This creature can’t be the target of spells or abilities.)
Vanishing 4 (This creature enters the battlefield with four time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)