Can Teemo be hidden from the chosen champion zone, and can a hidden card be played as a reaction on the same turn it was hidden?

Ruling: Teemo cannot be hidden from the chosen champion zone because the champion zone only allows playing cards (not hiding them), and hiding is a separate game action from playing a card. A hidden card cannot be played on the same turn it was hidden, only on subsequent turns.

Sequence:

• Question 2 scenario: Opponent hides a card at a battlefield, then activates Caitlyn's ability
• You react by playing Gust on Caitlyn
• Opponent cannot react with the hidden card because it was hidden this turn

Nuances:

• The champion zone specifically allows playing cards following the Playing a Card rules, but Hide is a distinct game action
• Hidden cards require being in hand to pay the hide cost
• Teemo Legend specifically lets you put something from the Champion zone into your hand (implying you need it in hand to hide)