Mercanary could use a small buff like +1/+1
No, that would made him definitely overpowered. A +0/+1 buff yes, but a +1/+1 buff no. 4/6 for 2
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in his upped version is clearly broken.
Anyway, I think Graviton serves better in a mono-gravity deck or in a
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deck, buffed by Adrenaline.