Whoa. This is insanely powerful, see mana vault and gem mine for comparably functioning mechanics

On a side note, I don't quite understand formshift... does only 1card get destroyed if they are destroyed, or do both?

I don't play or understand M:TG.

But I still love this and will promote this topic on the next page.

On a side note (myself being picky) it's technically "Power/Toughness"

I would recommend looking into the "morph" mechanic a little bit. If you play the panthera group as face-down morph creatures with something related to their element as their turn-up effect.

If you'd rather stay with how you currently have the formshift power, I'd consider making use of something like Imprint, or altering Formshift so that it RFGs (removes from game) the card rather than changing/adding a type to a card every time you activate the ability. You could even add rule text that sends the imprinted card to the graveyard rather than keep it RFGed.

I especially like the use of, er, Reynder's quote from Chapter 1 as the ironic quote that accompanies Magic cards. I'd love to see others picked out for other cards.

Hmm, I see. I like it better that way, but there's still a fewthings to address.

I recommend only allowing transformations at sorcery speed, otherwise battle math becomes ridiculously complicated, and it seems to me that it might be too strong of an ability to be able to switch willy-nilly for free. Also, what happens to enchantments or equipment on the formshifting creature?

Card reviews:

Combined attack: it's not bad, by any means, but it seems weak if the maximum damage is only 4. for 2 mana, though, it's probably fine.

cat fight: errata to 'all players'

Cat pun jar: this is wierd if you consider the stack. I'd recommend making it always active, not needing to be tapped, and maybe lower the damage to one or two.

SWAT team: the wording seems weird.... I can't think of a change, though xD

Cafeteria food: Interacts?

Gyeoknoho: ... gets -0/-3

Just my thoughts

School time!

So you have, essentially, 2 'speeds' of cards/abilities you can play. Instants, and sorceries (of course, there are other limiters and whatnot, but this just in a general sense.) Instants are usually cheaper, temporary effects and can be played any time you have priority. Priority is passed at every new phase (upkeep, draw, main 1, combat, main 2, end) and after every played card or other action that a player takes. The active player (the one who's turn it is) always has first priority, and then passes it to the next player. An instant-speed card/ability may be played any time you have priority. A sorcery-speed card/ability may only be played during your first or second main phase, and only on your turn. It may NOT be played in response to another spell.

Now, the stack is what happens when you play a spell, and someone else plays an instant-speed card/ability in response. For example: say I have a 2/2 artifact creature in play. It's my turn, and I pass priority from my 1st main phase so that I can enter combat. Now that he has priority, my opponent casts "Lightning" for 3 damage targeting my 2/2, which would normally kill my creature. However, I respond to that by casting Giant Growth (+3/+3) now there are 2 spells on the stack, neither of which have resolved. My opponent could respond again with a Counterspell, another damage spell, or anything really and add another spell to the stack. When no one has any more spells to cast you 'resolve' the stack, starting at the last spell played. In my case the Giant Growth would be applied first, making my 2/2 a 5/5, then the 3 damage: which isn't enough to kill it.

Note: If I had cast Giant Growth first, and he responded with Lightning Lightning would resolve before GG, and I would have a dead creature, which gives GG no target, and simply sends it to the graveyard.