You know you'll get it out on turn 3-4 and you just need to hit a way to mill or search for something to put in your yard early, and then you can move into midgame with a big threat on the table, and the ability to get it back without jacking up your commander tax repeatedly
Ice Age was designed by a group now referred to as the East Coast Playtesters (Skaff Elias, Jim Lin, Dave Petty, and Chris Page)
The "and/or" in the rules text is just to cover creatures that carry more than one creature type and ensures they are still eligible to activate this ability
A few I can think of off the top of my head are Rogues, Zombies, and Faeries
Glimmer of Genius and Hieroglyphic Illumination dont just feel different, they also play differently, and require different types of decisions and shells
Meanwhile, Thermokarst gives you a life sometimes, but theyre pretty much interchangeable cards and its much cheaper to buy