Trainer Cards are split into two types primarily: Items, which you can use as many of as youd like each round, and Supporters, which you can only use once per round
Where's the best place to put a Pokmon vending machine
The main body of the Disk retains the touch screen and single Spell and Trap Card Zone (which is also where the Field Zone is located) seen in D-Pads, while the Monster Card Zones and Pendulum Zones are located on the arm blade, which, like the 5D's future Disks, is composed of energy (likely the same "touchable Solid Vision" used in Action Duels) and is aligned parallel to the main body of the Disk
You can only use 1 "Castel, the Skyblaster Musketeer" effect per turn, and only once that turn
The one-two punch of Increasing Savagery with Sylvan Might to make any creature into a trampling monstrosity should be enough to finish off anyone who has lived long enough to see you accumulate enough mana to make it happen