[Uh-Nu-Buh]

Bug: I had the same problem. Remove and item and DM disappears.

DM useless: Well, maybe. I find cheap wyverns of use as bodyguards; fire drakes are good artillery support for nations like Abyssia; cave drakes are good to mix in with your infantry.... Maybe a bit overpriced, even with DM. It might be a fundamental cost problem. Instead of 8 gmes, maybe 4 gems? Compare them to other summoned units. 8 is indeed expensive for what you get. 4 would be about right.