Despite the TCG only having access to Blood Mefist as a prize card, it is perfectly legal for use in the actual game
They're not legendary though, so they're not technically viable as commanders, though that hasn't stopped players from including them as honorary commanders in Rule 0 conversations
What ends up looking like his death is quite dramatic, with him falling down the middle of a skyscraper and all, but it's subverted in that he turns out Not Quite Dead
While the Extra Deck was only comprised of Fusion and Synchro Monsters at the time of the card's original Western release (it was released in 2001 in Japan, when only Fusion Monsters existed in what was then the Fusion Deck), in modern play the card could bring out a whole host of Xyz, Pendulum and Link Monsters with ease -- were it not for the card's errata
I would like you to follow the example of Mist Valley Falcon
The two things to remember when playing Thunder Dragon is to always leave a light and a dark, and always go second