(Funny that this would come up just a few days after I was re-playing Lost Kingdoms 2 )

Wow, the cards so far are incredibly detailed and awesome. Good work. Regarding randomization and mana crystals, I agree with the others that having both restrictions is extremely limiting. I don't know if you've played the second game, but it does a couple things differently that actually make it easier to translate into DnD. They got rid of the arena for random battles and changed it to just fighting as you walked around. In order to accommodate both this and the fact that they also introduced Transform cards for navigating levels, they made discarding just go straight to the bottom of your deck. Since you can just stand somewhere out of range and cycle through your cards until you've got what you want (even stack the deck in order if you've got some time on your hands), I'd say to just let people cast out of whatever they've readied for the day. Mana crystals should do a fine enough job limiting them if you're modeling off psionic power points, and between the limit on top level cards and number of uses per card that should be enough that randomization isn't needed at all.

The only problem I'd see is the inevitable pile of Crystal Roses and Lizardman cards which would basically function as at-will until they're not. It's an effect you don't run into in the games since you don't have enough copies to try and pull it, but since you have unlimited copies with this, it's a bit of a flavor problem. Considering that you can't use more than one copy of your top tier and three of your second, I'd put a limit on how many copies you have of each card. Say you start out with two each of the cantrips and one each of the 1st rank, and you double your copies each time you get access to a new level of cards. It'll take 10 character levels to reach 32 copies of a card, long enough that if you really want it that bad, it's not gonna seem weird that you can do the same effect all day. More importantly, it means that while you've got 3 of your second rank cards, you won't have more than two copies of the same card within those three, then four copies of your third rank, and so on. It's an extra phantom restriction (when I've just said I don't like those, feh), but I think it does a more serviceable job of keeping the card flavor. Or it could just be more bookkeeping.

I'd make weapon cards default to using wisdom on the attack roll myself. Requiring feats to use your bread and butter cards well annoys me. The Red Lizard is currently weaksauce compared to the Lizardman, I'd recommend making them at least a d8 on each attack. Loving the Lizardman, though it might be a little much damage for a 1st level "at-will," maybe drop it to 2d6 (one oversized longsword, note that the lizardmen all use single handed swords). I like how you've done the independents, just writing short individual stat blocks and providing level up benefits for them, very effective. Skeleton could use some DR for it's trademark toughness (every time I take them out I wish I had them back in!).

Naturally when I was playing I was thinking about how I'd stat it up myself, probably a sort of "Mystic Crusader," with Crusader style recovery mechanics and a palette of spells and melee effects. I'm sure I would have built everything out of existing material, so I'm really impressed that you decided to take the hard road and build it all from scratch. I hope you manage to fill out the card list, good luck and I'll be watching!