I had an idea similar to this, but it would have been a 
creature (Bat / Dire Bat). Don't want to submit it and be accused of stealing ideas though, without asking you if you would be OK with my submitting the idea.
I also thought to bats when I had the echolocation idea at first. However, I thought it would make more sense to make it a permanent as the rewarding effect if for the player and not for the creature. Anyway, go ahead with your idea I have no objection. Eventually you can mention this card in the series box (only if you want).
