The Mountain Giant is a conversion from the 2nd Edition Expansion. You will need that expansion to use the Mountain Giant creature.
The archive includes the Mountain Giant card, the Rubble reference card and the Brute Strength, Crushing Force and Shortcut Lore cards.
These cards are designed to be printed on cardstock and will create bridge-sized cards when printed. I suggest after cutting out the card, trace a battlelore card over the printed card and trim to size.
You can also upload them to The Game Crafter and print using their bridge-sized card option.