ImpendingImpending is a keyword that represents four abilities. The first is a static ability that functions while the spell with impending is on the stack. The second is static ability that creates a replacement effect that may apply to the permanent with impending as it enters the battlefield from the stack. The third is a static ability that functions on the battlefield. The fourth is a triggered ability that functions on the battlefield. “Impending N—[cost]” means “You may choose to pay [cost] rather than pay this spell’s mana cost,” “If you chose to pay this permanent’s impending cost, it enters with N time counters on it,” “As long as this permanent’s impending cost was paid and it has a time counter on it, it’s not a creature,” and “At the beginning of your end step, if this permanent’s impending cost was paid and it has a time counter on it, remove a time counter from it.” Casting a spell for its impending cost follows the rules for paying alternative costs in rules 601.2b and 601.2f–h.
702.177. Exhaust (CR 702.176) 3—
Whenever Lurker in the Deep enters or attacks, seek a nonland card.
Whenever you seek one or more cards during your turn, conjure a duplicate of each of those cards into your hand, then
manifestTo manifest a card, turn it face down. It becomes a 2/2 face-down creature card with no text, no name, no subtypes, and no mana cost. Put that card onto the battlefield face down. That permanent is a manifested permanent for as long as it remains face down. The effect defining its characteristics works while the card is face down and ends when it’s turned face up.
Any time you have priority, you may turn a manifested permanent you control face up. This is a special action that doesn’t use the stack (see rule 116.2b). To do this, show all players that the card representing that permanent is a creature card and what that card’s mana cost is, pay that cost, then turn the permanent face up. The effect defining its characteristics while it was face down ends, and it regains its normal characteristics. (If the card representing that permanent isn’t a creature card or it doesn’t have a mana cost, it can’t be turned face up this way.)
If a card with morph is manifested, its controller may turn that card face up using either the procedure described in rule 702.37e to turn a face-down permanent with morph face up or the procedure described above to turn a manifested permanent face up.
If a card with disguise is manifested, its controller may turn that card face up using either the procedure described in rule 702.168d to turn a face-down permanent with disguise face up or the procedure described above to turn a manifested permanent face up.
If an effect instructs a player to manifest multiple cards from their library, those cards are manifested one at a time.
If an effect instructs a player to manifest a card and a rule or effect prohibits the face-down object from entering the battlefield, that card isn’t manifested. Its characteristics remain unmodified and it remains in its previous zone. If it was face up, it remains face up.
If a manifested permanent that’s represented by an instant or sorcery card would turn face up, its controller reveals it and leaves it face down. Abilities that trigger whenever a permanent is turned face up won’t trigger.
See rule 708, “Face-Down Spells and Permanents,” for more information. (CR 701.40) those duplicates.