Creature: 12
3x Claw
2x Rag Rappy
2x Recon
3x Saint Rappy
2x 7-point-creature-of-your-choice

Action: 9
3x Kamikaze Attack
6x Defense Cards Of Your Choice.

Assist: 4
1x Dice+1
1x Dice Fever
1x Legacy
1x Reqiuem

As you note, that's only 25 cards. The 5 remaining cards you can use to customize this deck.

Attack=6, to help your 1pt creatures do some damage, before they die.
Bequeath, Dice+1, Dice Fever,, Reqiuem, Legacy. All of these can help raise your chances of getting higher dice.
Exchange. If you set Dice Fever, you'll roll a 5/5, allowing you to play the extra 1 or 2 creatures you need for Legacy, then playing Exchange to take your Attack Dice for your Defense, so you can have a total of 9 points to play with.
More defense cards, especially ones that can block stuff like Paralysis Death, Frozen Death, Megid, Major Death, so when you DO have your 7 point creature out, it won't get killed by something like that, as most 7 pointers have way high HP
Techs. If you're 7 point creature is going to be used for casting techs, you'll need to have some in your deck
Snail's Pace. This'll help keep those pesky Hunters away from you long enough to get your 7 point creature out.

Anyways, this deck is made SPECIFICALLY to allow you to play your 7 point creature, while keeping the enemy at bay. Even if you can't get your 7 pointer out within 10 turns or so, you can still push the enemy around (1pt creatures + Attack=6, or Saint Rappy), as well as what you decide to use for the 5 cards you chose to put in there.

Memoru. She can help with her Snatch ability
Ohgun. His Contact Halfguard is always great.
K.C. His range allows for great back up, toss a Attack=6 out, and he can hit for 6, from 3 blocks away