Ancient Kalidnay is one of the best realms in Spellfire. When you first drop it, it's placed in the vertical orientation, and is considered both a Dark Sun and a Ravenloft realm. At the end of your turn, you may choose to voluntarily raze it. If you do, you take another turn. That's primo. If you choose to save the extra turn for later, you can take that risk - although Kalidnay has no movement restriction and no power that is useful in battle. I always use my Kalidnay immediately, because it's just too difficult to keep it alive and unrazed (unless it's buried deep in your formation somewhere, protected by other realms).
Unrazing Kalidnay results in it being shifted to a horizontal orientation, which serves as a reminder that its special power has already been used. It's a one-shot deal, you can't take repeated extra turns. I rarely unraze Kalidnay, but I usually don't replace it with another realm right away, either. Why not? Because once your Kalidnay is in the discard pile, your opponent is free to play his own. Just about every deck will contain a Kalidnay, you can bet on that!
Which brings us to Kalid-na, the hideous creature who in the D&D mythos comes from Ancient Kalidnay. In Spellfire, especially in The Antigonish Variant, Kalid-na is a great choice for any deck containing wizard spells. He is high level, can use psionic powers, and stops anyone from playing Kalidnay. Assuming you don't run Kalidnay yourself (whoops!), this is a primo power. Not only are you removing your opponent's access to one of his realms, you are in effect stripping away one of his turns - the extra one Kalidnay would have given. The only downside is that said opponent is coming after your Kalid-na with every champion-killing card at his disposal!
Next time: The worst Millennium (sticker set) cards! Yup, I'm going there.