Those cards are considered to be "used to craft" that permanent as long as they remain exiled and the permanent remains on the battlefield, even if the permanent's controller changes or some of its characteristics change (because of a copy effect, for example.) If the materials required include multiple objects, you may exile some of them from among permanents you control and the rest from among cards in your graveyard
Aquatic Alchemist is one of several commons that really help as an early blocker, it can pull a lot of duties in the deck as its adventure gets you a spell back (on top of the deck isnt ideal but it's workable), and when you trigger its ability it goes from a decent 1/3 blocker to a 3/3 body that is able to pressure or trade upwards
Play your very first game in a guided battle of Captain America versus Iron Man
These cards offer players a unique method of countering attacks
If the card is truly rare and valuable, slight changes to the pop report wont matter
Note : Values are based on publicly reported sales and market data available in 2026