A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
Battle: If Wotan is opposed: Look at the top 4 cards of your Fate deck. You may switch one with a card from your hand. You may take an additional Battle action.
What happens after Wotan looks at the top 4 cards of his controller's Fate deck (regardless of if his controller does/does not switch a card from his hand)? Does the player's Fate deck need to be shuffled?
Battle: If Wotan is opposed: Look at the top 4 cards of your Fate deck. You may switch one with a card from your hand. You may take an additional Battle action.
What happens after Wotan looks at the top 4 cards of his controller's Fate deck (regardless of if his controller does/does not switch a card from his hand)? Does the player's Fate deck need to be shuffled?
No, you don't need to shuffle.
"Searching" causes a shuffle, but merely "looking" does not.