You can remove three +1/+1 counters from Runaway Steam-Kin to generate three red mana
Crucible of Worlds was a fan generated card, and is getting pricey, so I could easily see that here
The fact that its also an unblockable creature against red decks is an extra bonus
But in a different world, Saheeli the Gifted is the kind of planeswalker I would have expected to headline an entire block
However, her ability certainly makes her stand out
It might hold its own against other decks that just want to cast cool, expensive cards bound only by their color, but it crumbles against anything with a plan more cohesive than cast a spell each turn. Generic good-stuff decks can work, but they require much stronger cards and a better curve than what this deck has