The major problem is that CMR foils can become dry and curl, especially if you live in a low humidity climate, home or place of business, turning your new cards into the shape of Pringles
But there are also many situations where shutting down the player most likely to try to cast multiple spells in a turn, while retaining your own ability to cast multiple spells is better
Zidane, Tantalus Thief Zidane is interesting here as a gift commander, who is also sort of a Threaten commander and working with blinks to be very interesting for johnny players
Purphoros, God of the Forge will love this
There have been plenty of creatures that bleed your opponents out as creatures die, but Blood Artist popularized the ability, and paved the way for an endless wave of clones and spin-offs
The Historic version in particular suffers against these spells: Scurry Oaks combo has to wait a turn to win with attacking squirrel tokens, and the nature of clicking through triggers on Arenas clock means they will usually settle for their infinite combo only gaining twenty or thirty life before their turn times out
