Talk:Energy Siphon/@comment-5277710-20130714100123/@comment-64.147.18.52-20130715184654

It's not double the cost, it's one-third, or 33%, more cost rounded down (so Energy Siphon would cost 9 instead of 7).

And yes, you are being... encouraged to polarize your aura slot. This may change due to the feedback, but it's how it works currently.