Let’s start having polls on some cards that we currently think are too costly to be useful. For example, here is Complete Disregard. As many have pointed out, it costs 9 more than Reave Soul, which does the same thing except for the Devoid / Ingest.
It is funny it costs as much as it does, killing a 3 power creature is useful if it only takes one turn to get the mana for it.
Turn Against, Reave Soul, Lithomancer’s Focus, and Demolish are all situational cards, but since they all cost 3 mana (Reave Soul for an almost identical ability), they can be switched to at any time, paid for 99% of the time in one turn, and pitched if they are not needed.
Since 3 power creatures rarely stay that way due to their general cheap cost (almost all 7 or less), the card is only really effective if it can be cast in 1 or 2 turns.
Yes, I think the increased cost is supposed to make up for the Devoid / Ingest mechanic, but currently this increase seems too high across the board. It’s very difficult to generate enough void gems to match a significant fraction of them, unless you have already managed to cast one of the very expensive creatures (e.g. BoBG or UtCH).
I look forward to voting ‘I don’t see how this card could be useful in its current state’ in many, many polls to come.
I figured we could have a number of these polls, but it may be most helpful to make our point with the “obviously unusuable” cards and working our way up. 
I’d use it if it’d cost 5 maybe 6 at most
Or if it didn’t have the 3 or less rider. If ingest was much more common like with the big mythics I could see devoid being OK, but if they are all costed because of said mythics that hardly anyone will get a plurality of them then they are not playable for most people.
Actually, even if the “3 or less” weren’t there, Grip of Desolation is an uncommon that costs one less and produces two Void gems. Scour from Existence is a colorless common that any deck could use, it costs 12 and produces three Void gems.
Both of these cards would be superior to a hypothetical Complete Disregard with the “Power 3 or less” condition removed, assuming the player wants Void gems. Black has some even cheaper “destroy creature” spells that do not create Void gems (Unholy Hunger, Ruinous Path), but they are rare so perhaps not as directly comparable.