For example, if we look at a card like Mindbreak Trap, it says exile any number of target spells. It would be to powerful if you could exile any number of creatures on the battlefield, so this only refers to cards that are on the stack
So, it is a very useful Ability to use to score some strategic points
However, there is another, more unique variety of ability, and this kind of ability is why a specific Charmeleon is often used in Charizard decks in the current format
Thats great for some removal on a big enough creature, especially with lifelink, or a small creature with deathtouch
The Lost Caverns of Ixalan (LCI) brought us a lot of fun and pricey pieces (more on that later), but Mana Crypt is not one I expected to see
Since she can't be countered, most decks have no ability to interact with her