This is a very relative topic and also lends on how great this game is by the randomness of the cards. I base this on the Lightning Dragon:
When we bought the game, the guy working at Gamespot was telling us about this Lightning dragon, which of course is not in the first game. My brother and I played it, and after awhile we started to think that the guy was lying, since we never saw one. I tried to reason that maybe he's talking about the Wyvvern since it does look gold, and after all, they ARE dragons, right?
I had played about 50+ games and found no such card. However, my brother played about 5 and guess what HE got? The lightning dragon card.
I continued to play, and had played 80+ games, far more than anyone else in the house, but no Lightning Dragon. Then my older brother's son visits one weekend, and plays ONE game, his very first of Culdcept Saga....
Guess what HE got?
Yep! The Lightning Dragon. I wasn't so mad, just kinda funny that I have now played close to 100 games but have not gotten one of those, but collectively two guys play about 6 games and have one each between them.
I say all this in jest because I don't mind, and it lends to the excellent replay value of this game. Anybody else played looking for an elusive card that you have yet to get?
Kelpie is a great card, definitely. I used that card to gain probably half the avatar parts... the AI has real trouble dealing with it (it doesn't seem to grasp the idea that it's going to stop there no matter what). As long as you can protect it, Kelpie is a big ol' cash cow.
Word of Recall is a life-saver. I've lost track of the number of matches (online and offline) that Word of Recall has bailed me out. Level 5 land between you and the castle? Word of Recall. Trying to beat someone else back? Word of Recall. Want to deny someone their lap bonus before they pass the last checkpoint? Word of Recall. Gotta love it.
I have all of the cards, but I need more of Goblin's Lair and Freeze Cyclone. 1 of each of those just doesn't cut it in a couple of my books.
When I played Culdcept, I received several Kelpies and a similar card "Old Willow" I think, for the red deck. Both did kinda the same thing, although I didn't use Kelpie as much as I would have liked.
But with the Saga, I do have I think 2 Kelpies. I used one in a blue deck that mopped the floor with Ticomon, and allowed me to actually earn several avatar parts by using the loop and get 99,999 gold and place a creature on every piece of land.
Word of Recall I am not sure I have yet, but after over 100 battles, I know there are over 100 cards I still don't have. Very exciting...but still no Lightning Dragon...when I get one, drinks are on the house (soda of course... and generic at that)