Why should the upped version be the smaller one? Usually ability exceed with more attack and/or hp, so even though its cheaper i think the unupped version has more use than the upped one.
General thing, as i pointed out at some other card ideas, new cards should add diversity and this is not new in a sense that there is alrdy mutant as an ability, as a card and all these ability already exists too. That's why i think it won't make it through the armory into the game.
Mutation may already be in the game, but its a multicard combo no matter how you slice it.
Thanks to openEtG I've gotten a chance to test this card out a bit (granted there are lots of differences but it still works reasonably well for play testing new stuff).
Right now, mutation based decks take quite a bit of work to pull off well. Spider cow makes inserting random madness much easier.
I was skeptical about having the upgraded version weaker, after play testing I quickly found that it is actually far superior due to the much lower cost. The reason is that the most important part of the card is the fact that it gets a random ability. The HP and ATK are surprisingly much less relevant. If it needs to be tougher, you can always use chaos power.
Case in point, consider the fractal combo.
It takes a total of 38
to get 7 unupgraded spider cows. It takes only 17
to get 7 micro spider cows.
7 cows = 7 chances to get the ability you need (steal, destroy, and lobo being the most useful)
Lastly, the upgraded being cheaper makes it a nice compliment to micro abom when all you need is a cheap critter to pop butterly effect or improved mutation onto.
I have to hand it to moomoose, he comes up with some very brilliant card ideas.