Whoops, I was so busy thinking about Gitaxian Probe that I forgot about the other Phyrexian mana spells. That does make me wonder if it might shift to UB Delver or UR Delver for better creature removal.Delver also loses access to the variety of spell effects they get out of Phyrexian Mana spells. Specifically losing Dismember and Gut Shot is no small loss. Gut Shot was important for Delver to fight decks reliant on mana creatures and gave Delver something useful to do against Thalia. Dismember gave Delver a way to actually kill larger creatures like Restoration Angel that are now much more of a problem. And these effects went extremely far with access to Snapcaster Mage.