Yusei and Jack both have friends to fight for, along with the protection of Satellite and New Domino City
Deciding between attacking a Leader or a Character depends on your deck, the matchup, and the game's current state
They can deal out lots of damage but "burn" generally refers to instants and sorceries that do direct damage
The Emperor, Hell Tyrant (Yawgmoth, Thran Physician) Yawgmoth, Thran Physician is a Modern staple (there's a whole deck named after him), so the Emperor art would be a nice addition to die-hard fans of the deck
(You may cast a spell for its prowl cost if you dealt combat damage to a player this turn with a creature with any of its creature types.) You can cast a spell for its prowl cost any time in a turn after a creature you control of a matching type has dealt combat damage to a player
Noboru Gongenzaka also used the cost of the destruction effect of the super-heavy demon Tetsudo-O as an action card