Creatures (31) 3 Goblin Vandal 4 Goblin Recruiter 4 Goblin Matron 4 Goblin Lackey 2 Kiki-Jiki, Mirror Breaker 3 Goblin Warchief 1 Goblin Sharpshooter 4 Goblin Piledriver 1 Gempalm Incinerator 1 Siege-Gang Commander 3 Goblin Ringleader 1 Skirk Prospector Lands (18) Spells (11) Sideboard Once you stack your deck, every Ringleader will hit four more Goblins, meaning you can basically just draw whatever sixteen Goblins you want (and thats not even factoring in Goblin Matron)
An EX-based deck is not only viable but often a popular 'meta' pick, because their strengths can beat down the opponent before their Pokmon cards can get revenge
Uh, okay then, Hydro-Man, Fluid Felon, sure
Running a blue-black dual land that can also be used to cast either Force of Negation or Grief (both Modern staples) for free could just be an appealing enough proposition on its own in the right deck
While these arent super common, its important to understand that these costs cant be paid with any color of mana the same way generic costs can