It's already the best-selling Magic set of all time, and no matter how many players complain about the prices, and how loudly they complain, pretty much any Final Fantasy product gets sold the moment they go on sale
Giving your opponent access to that isn't always ideal, but you get it first, so I think it ends up benefitting you more often than it benefits them
They're an even better idea if you can save money
With a Vivi under an Agatha's Soul Cauldron and a Geralf, the Fleshwright in play, every additional spell you cast creates a zombie with at least one counter on it
Meren gives you an experience counter whenever a creature you control dies, meaning its very easy to generate a huge number of these counters in a sacrifice deck
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