Unveil {5} (Start the game with this identity face down in the command zone. Turn it face up any time for its unveil cost.)
When The Bodyguard is unveiled, until your next turn, prevent all damage that would be dealt to target player and each creature and planeswalker they control.
Illustrated by Hokunin (Prokopii Osipov) @ DeviantArt
The replacement effect stops as your next untap step begins, before you untap your permanents. If this causes any state-based actions to become applicable, or if any abilities trigger, those are handled during your upkeep.