The main reason for this is that a lot of the older MTG formats, namely Modern and Legacy, use cards that dont cost much mana
6 Jace, Wielder of Mysteries War of the Spark introduced static abilities on Planeswalker cards, which made Jace, Wielder of Mysteries an alternative win condition for some decks
Partner (You can have two commanders if both have partner.) At the beginning of each of your postcombat main phases, you may pay X life, where X is the number of opponents that were dealt combat damage this turn
Lillies Clefairy ex (Special Illustration Rare) $134.82 Card Number: #184/159 Rarity: Special Illustration Rare The crown jewel of Journey Together
From spikes who don't care, Iona, Shield of Emeria
Thats a good cost for a good effect, but it gets better as long as youre playing the right kind of Creatures