Flash
When Niambi enters, you may return another target creature you control to its owner's hand. If you do, you gain life equal to that creature's mana value.
{1}{W}{U}, {T}, Discard a legendary card: Draw two cards.
If a creature on the battlefield has {X} in its mana cost, X is considered to be 0.
23 Jun 2020
If the target creature is an illegal target by the time Niambi's triggered ability tries to resolve, the ability won't resolve. You won't return the card from the zone it moved to or gain any life.