way back when the CIA forum was in its infancy, we avoided using the same names for cards as those which had already been created, but that faded. for what its worth, i too took a stab at the griffon, it may still be in the polls, but you can check my portfolio if youre curious. but today, it isnt an issue if two cards are covering the same theme.
as far as using dive, while fitting, seems fairly trivial and not really all that interesting, and redundant. guard would be slightly more interesting, but may overshadow the respective earth creature. the griffon is a cool creature, but has been difficult to come up with a novel mechanic for, so it would be worth continuing to explore the theme and see if you can come up with something else.