Say I have a Shambling Vent. I animate it, then play Dauntless Bodyguard targeting it. At the end of turn, Shambling Vent returns to being a land. Next turn, opponent uses a land destruction spell on Shambling Vent. Can I sacrifice Dauntless Bodyguard to give Shambling Vent indestructible, thereby countering the land destruction spell?
Relevant text of Dauntless Bodyguard:
Sacrifice Dauntless Bodyguard: The chosen creature gains indestructible until end of turn.
The question hinges on whether this ability still works given that Shambling Vent isn't a creature at the time Dauntless Bodyguard is sacrificed.