Deathrite Shaman would often take control of a game on its own, and all at the low cost of a single mana
The "Hex Maniac" Supporter card from the Pokmon TCG XY series expansion Ancient Origins is a great example
Optional Cards that can be cut without hurting core consistency
That's Mr Bone Dragon to you
Adventurer's Inn Balamb Garden, SeeD Academy Baron, Airship Kingdom Capital City Clive's Hideaway Crossroads Village Eden, Seat of the Sanctum Gohn, Town of Ruin Gongaga, Reactor Town Guadosalam, Farplane Gateway Insomnia, Crown City Ishgard, the Holy See Jidoor, Aristocratic Capital Lindblum, Industrial Regency Midgar, City of Mako Rabanastre, Royal City Sharlayan, Nation of Scholars Starting Town The Gold Saucer Treno, Dark City Vector, Imperial Capital Windurst, Federation Center Zanarkand, Ancient Metropolis