That card is so confusing to me. I'll probably never play it with the Fusion ability.
What exactly is confusing about it?
Thousand Dragon wrote:
Fusion: Before your attack, if you move two different [Thousand Dragon Fusion] from the field to your prep area, you may move this die from this card to your prep area.
Only two cards in YGO DM have the Fusion Material 'affiliation' - Time Wizard and Baby Dragon. Once you have one of each fielded, at any time before your attack step, you can move them to your prep area. If you do so, you can move the Thousand Dragon die from its card to the prep area. Next turn, you get to roll the Thousand Dragon die (as well as the Baby Dragon and Time Wizard dice). That's all there is to it.