It inspired me to utilize World Championships Survival of the Fittest s for my first Premodern deck, and I was greatly thankful for the discount
You can argue that mana is the most important resource in Magic, so getting more of it is one of the best game actions you can take
With flying, vigilance, and indestructible, it also grants indestructibility to all your other permanents
The many cheap burn cards in red helped get the hideous, woefully flawed, Jackal Pup through, for lots of damage, when the seemingly much stronger white version would be scared, sitting at home, for fear of tussling with a 2/2 first striker or simply a larger creature
They differ only in one feature, which is the key in our situation
Complete sets are usually overpriced but you can get lucky depending on how and when they are listed