Theyre powerful, immortal, and they come with a whole host of awesome powers
Unlike a lot of other similar effects, Shivan Wurm isn't dithering around
Starter decks are relatively inexpensive considering their contents when they can be found at MSRP, making them a much easier way to start playing than building a deck purely out of booster packs or aftermarket singles
Cold-Eyed Selkie, Herald of Secret Streams, Iridescent Hornbeetle, Managorger Hydra, Sakura-Tribe Elder and Trygon Predator have all been subbed in
Lilysplash Mentor's ability costs three mana, and can only be done at sorcery speed
The Angel only costs five mana but Engine is colourless only and can be made with things like Grand Architect more quickly