It is still a creature spell, of that name, with the CMC of the original card (not the mutate cost)
If there is an issue we will work it out
Treat phased-out permanents and anything attached to them as though they dont exist until their controllers next turn.) Illustrated by Sam Hogg Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Not Legal Brawl Not Legal Legacy Legal Comp
If you count up all of the reprints valued at $3 or more, you'll see that Commander 2018 averages four a deck, while Commander 2017 had 6.4 and Commander 2016 had more than eight, which means the number of valuable reprints has been cut in half in two years (while MSRP increased from $35 to $40 at the same time)
Magic: The Gathering Comprehensive Rules, 303 Enchant and 702.5
Phyrexian Tower is a clutch sacrifice outlet, but thats all it is