well, yes i have a better idea of what you want, but that is a lot of design and I don't think that this place is where you will get all done. I can give you some more pointers though:
1. 12 creatures slots. You would need either to limit it on program side or DB side. I would enforce it on db side with a table designe like:
playerid int not null,
creature_slot enum('1', '2', '3', '4', '5', '6', '7', '8', '9', '10', '11', '12') not null,
creature_type int not null,
...
unique index player_creature(`playerid`, `creature_slot`),
...
Making sure no illegal values can me stored, the unique index would ensure you a max of 12 creatures per player.
And for every other requirement, try to find out how you would do it.
Good luck,
H.