It also screws up the math for your opponents, suddenly, they get a 2:1 since they remove your card with a card of theirs and they get their card back (assuming you are getting anything useful from the saga) that being said if this is for like an enchantress deck, you get a trigger off the ETB and don't care so much if it goes away
From there, the player can easily pump the creature, gain life (probably the weakest ability), or weaken another creature
It can help to make a deck hum, after all
These are just some of the cards that you can use to fight back against board wipes, or you can use them to protect your things when you cast your own
There are also other types of card covers, such as dark card covers, which cover the back of each card
If your opponents can't deal with Evasive characters, they can exert themselves to draw cards and gain lore with no fear of retaliation aside from outright removal