This deck only plays 21 lands because Experimental Frenzy is best with lower land counts, which is tricky because it costs four mana to play initially, but this is where Skirk Prospector, Wily Goblin, and Runaway-Steam Kin come in, allowing you to cast your four- and five-mana spells with fewer than four lands
Once it triggers, it won't trigger again as long as the ability is on the stack
Its a 'may' and that means that if your opponent does not have any creatures you can exile, the flip does nothing
For example, take a look at Eureka on TCGplayer
Most white removal either destroys or exiles, and it has access to the widest array of mass removal
Because it can handle the low-toughness threats of aggressive decks and the heavy artifact synergies of the TMNT era, it remains a red staple