This is important because it underlines a key part of defining what combo decks are, and how to easily recognize them: A combo deck is built around the combo , and often has a very hard time winning if unable to assemble the combo
Centering Here's a big one
You can copy a Maze of Ith to defend against an attacker on one turn, then copy an opposing Tatyova, Benthic Druid to gain some extra value on the next
[Activate:Main][Once Per Turn](2) (You may rest the specified number of DON! cards in your cost area.) : Set this Character as active
The second thing is that, well, stealing your opponents Dragons is awesome
At worst, this is a 5 mana, draw multiple cards spell, essentially, assuming you immediately kill it for its -3 ability