I love this card so much. Sometimes it feels hard to stick to your Seeker. You lag behind while prepping for enemies, but now you don' t have to! Just plop this down in the turn you play your weapons and ride on the back of your Seeker friend. Another tool to compress Guardian actions to focus on protecting their friends. Whereas Heroic Rescue, "Let me handle this!", and Taunt are all fantastic cards, the reusability of Safeguard makes it a great choice. It's also easy to play via cards like Ever Vigilant.
Furthermore, when your Guardian finishes using all 3 of their actions to do combat, they cannot be by the Seeker's side during the next mythos phase when the Seeker has moved to a new location only to spawn another enemy. Safeguard makes sure the players are in sync and there isn't a stagger where the Guardian spends 1-2 actions to catch up to the Seeker surrounded by enemies.
It also makes the movement cards off other investigators twice as good. Combo with things like: