It leads to very long and unfun combo turns and is extremely strong with staples like Paradox Engine An incredibly easy combo and mana-generation card, with all the artifact mana played in Commander
You need a little something extra to help the cause a lot of the time, and flexibility is often a must
However, there are two ways to play a Shift character: You can choose to pay the Shift cost and play the character over the character named in the y part of the ability
The initial asking price for Teferi, Temporal Pilgrim has been (unsurprisingly) as high as $50 a card, but it's lost steam in the past several weeks
Worst-case scenario, we can untap the Sol Ring we just used to cast that instant or sorcery, and the ceiling is much higher
Some folks might design packages around specific cards