Whitemane Lion's ability doesn't target any creature, therefore no player may take actions between the time you choose the creature to return and the time you return it.
08-12-2022
wotc
You may return Whitemane Lion itself to its owner's hand as its triggered ability resolves. If you don't control any other creature, you must return it.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.