I think it may be fine now, it shouldn't be use in first turn with nova or 2upped rainbow tower.
4
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to destory 3 permanment and get a blackhole, it is still power when it on your battlefiled. but it is slow because of 4
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so I think it is fine now.
and it is weak in first turn. If it is 0/15, you can SoF+ gravity force. it is still powerful.
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have charge,unstopable, not really need PC to destory shield.
To do summary, I think sof is just Ok now.