As an additional cost to
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) this spell, you may
collect evidenceTo “collect evidence N” means to exile any number of cards from your graveyard with total mana value N or greater.
If a player is given the choice to collect evidence but is unable to exile cards with total mana value N or greater from their graveyard (usually because there aren’t enough cards to do so) they can’t choose to collect evidence.
A spell that has an ability that allows a player to collect evidence as an additional cost to cast it may have another ability that refers to whether evidence was collected. These abilities are linked. See rule 607, “Linked Abilities.” (CR 701.59) 6.
DestroyThe only ways a permanent can be destroyed are as a result of an effect that uses the word “destroy” or as a result of the state-based actions that check for lethal damage (see rule 704.5g) or damage from a source with deathtouch (see rule 704.5h). If a permanent is put into its owner’s graveyard for any other reason, it hasn’t been “destroyed.”
A regeneration effect replaces a destruction event. See rule 701.19, “Regenerate.” (CR 701.8) all creatures. If evidence was collected,
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) a card from an opponent's graveyard. Then
searchTo search for a card in a zone, look at all cards in that zone (even if it’s a hidden zone) and find a card that matches the given description.
If a player is searching a hidden zone for cards with a stated quality, such as a card with a certain card type or color, that player isn’t required to find some or all of those cards even if they’re present in that zone.
If a player is instructed to search a hidden zone for cards that match an undefined quality, that player may still search that zone but can’t find any cards.
If a player is searching a hidden zone simply for a quantity of cards, such as “a card” or “three cards,” that player must find that many cards (or as many as possible, if the zone doesn’t contain enough cards).
If the effect that contains the search instruction doesn’t also contain instructions to reveal the found card(s), then they’re not revealed.
If searching a zone is replaced with searching a portion of that zone, any other instructions that refer to searching the zone still apply. Any abilities that trigger on a library being searched will trigger.
If an effect offers a player a choice to search a zone and take additional actions with the cards found, that player may choose to search even if the additional actions are illegal or impossible.
An effect may instruct a player to search a library for one or more cards more than once before instructing a player to shuffle that library. This is the same as a single instruction for that player to search that library for all those cards. The player searches that library only once.
If multiple players search at once, each of those players looks at the appropriate cards at the same time, then those players decide in APNAP order (see rule 101.4) which card to find.
If an effect instructs a player to search outside the game for a card, that player may choose an appropriate card they own from outside the game. (CR 701.23) its owner's graveyard, hand, and library for any number of cards with that name and
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) them. That player shuffles, then draws a card for each card exiled from their hand this way.