Kefnet the Mindful
Legendary Creature — God
Flying, indestructible
Kefnet can't attack or block unless you have seven or more cards in hand.
: Draw a card, then you may return a land you control to its owner's hand.
Chase Stone
Rulings
Once Kefnet has attacked or blocked, it will remain in combat even if the number of cards in your hand becomes six or fewer.
(wotc • 2017-04-18)
While resolving Kefnet's activated ability, you don't choose which land to return to its owner's hand (or whether you'll return one at all) until you see the card you draw.
(wotc • 2017-04-18)
Rulings
Once Kefnet has attacked or blocked, it will remain in combat even if the number of cards in your hand becomes six or fewer.
(wotc • 2017-04-18)
While resolving Kefnet's activated ability, you don't choose which land to return to its owner's hand (or whether you'll return one at all) until you see the card you draw.
(wotc • 2017-04-18)