As a PSA, let me tell you about a lesson learned the hard way. Nowhere on either manufacturer site will you find this, but if you attempt to power a LF 12+ through the MIDI cable in an AxeFX II, you will burn up a component in your AxeFX, and phantom will no longer be an option. The AxeFX can't support the amount of current the 12+ requires, but that's not noted anywhere in either manufacturers' documentation.
Jeff at Liquid Foot has a hidden option (on the order page, look under "Special Notes") for an external unit that will prevent this from happening. But if you're going to use phantom power, this is NOT an option, it's a requirement.
I have a support email in to FA, because I'd really like to not have to send the AxeFX back in for a repair.