If “Legendary Jujitsu Master” is destroyed, removed from play, or flipped face-down by the effect of the monster he battles with, “Legendary Jujitsu Master”’s effect is still applied and the monster is returned to the top of the Deck.
If “Legendary Jujitsu Master” is changed to a Fiend-Type or a Zombie-Type by “DNA Surgery” and is attacked by “Getsu Fuhma”, “Getsu Fuhma”’s effect is Step 1 of a chain because the turn player is Step 1, and “Legendary Jujitsu Master” is Step 2. “Legendary Jujitsu Master” resolves first and “Getsu Fuhma” is sent back to the top of the Deck, then “Getsu Fuhma”’s effect resolves and “Legendary Jujitsu Master” is destroyed.
If you have “Destruction Punch”’s effect, and your opponent attacks your “Legendary Jujitsu Master”, you resolve the 2 effects in a chain with the controller (the defending player) choosing the order.