Lets look at some of the best adventure cards and see exactly what makes the mechanic so interesting and powerful
This version of Teferi can +1 to untap an artifact, land, and creature you control
Marrow-Gnawer is capable of creating dozens of tokens at a time, and when combined with certain artifacts, can make enough tokens to burn everyone out of the game with Mirkwood Bats
Nissa, Who Shakes the World is cleanly answered by Noxious Grasp, as well as Teferi, Hero of Dominaria
Again, for only three mana, you draw two cards, you gain a life, an opponent loses a life, and you are 25% of the way to transforming Sephiroth
Anybody who played during Theros Standard is going to remember that Domestication was a format staple and Connive is doing something very similar