There arent any discount beyond $0.75/card
Shanna, Purifying Blade Shanna, Purifying Blade is a lifegain commander that benefits from steady lifegain

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Same mana cost, triggers precombat, swaps two life for a card, one for a Token or three for a 3/2 and you can do a few here and there or all three
That said, after running into some failures with Mew myself, I wasn't surprised to see it underperform