If you can't pay the cost, you will still get the spell
If it's a Siege, it will still be exiled when the last defense counter is removed from it, and its controller may still cast it transformed without paying its mana cost
Seriously, the decklist reads like something a first-time Magic player wouldve built in 2013, with things like Deadbridge Chant, Garruk, Apex Predator, and Yavimaya Elder floating around
Bayou ($250 - $500) - A dual land card from the original Alpha set that counts as swamp and forest, granting a black or green mana per turn
The four-mana enchantment-themed planeswalker is certainly interesting, but is much more of a build-around than a typical powerful planeswalker that could easily slip into any deck of the matching colors
You might be familiar with the very simplistic monocolored precons (Welcome Decks) that are typically handed out to new/learning players at your store