Players highly value most dual land cards, but Underground Sea is one of the most difficult to get your hands on because of its high price tag
Rydia is even a discard outlet for Yuna, Hope of Spira, so someone gets to live the dream of discarding Bahamut for Yuna to reanimate
Chandra, Torch of Defiance is the red Swiss Army Knife: almost any deck with red in it would be happy to make use of her abilities, but her impulse draw ability is yet another way to generate even more value
You draw a card and you lose 1 life
In the real world give me Mine Collapse instead
Plus, since they're all only one color, it'll hopefully lead to straight forward gameplay, since you won't have to worry about mana fixing