I've got a BBEG who's a fully rolled out PC for all intents and purposes. Paladin/Guardian(mythic). She has the Invincible Stand path ability which allows her to basically turtle up hardcore, giving her a DR20/- so long as she doesn't move. Would a reflex save be considered as movement for the sake of negating the DR20/-? The actual text of the ability reads "if you choose to move or are moved by another creature the protection ends immediately."
I want to say it would not negate because a reflex is not a move action, but the specific spells we're looking at are like Entangle and Obsidian Flow, ones that merit reflex to prevent entanglement and take half damage.