Even without a voltron player at the table, whens the last time you had a game without Lightning Greaves, Swiftfoot Boots, Shadowspear, or any of the Sword of cards getting played
The classic here is the Vineyard from Tempest that gave everyone two Green mana, and then it was played in Standard since mana burn was a thing to kill those who couldn't use it
While the Future Sight frame was busy providing the first foils for a handful of cards, the rare and mythic rare sheet was busy going the other way
(It's an artifact with ", Sacrifice this token: Add one mana of any color.") Gadrak can't attack unless you control four or more artifacts
The cost reduction of the activated ability applies only to the generic mana component of the activation cost
Creatures offer a lot of card quality in the cube as well