UW Control decks typically play with a few Snapcaster Mages, and that 2/1 Wizard is going to rummage through the graveyard to find the perfect spell to flash right back
This can be pretty powerful if you have a way to cast enough spells to ult him immediately upon transformation
Its requirements are steep, but they also create an incentive for players to include blue creatures in their decks
Its monocolor, instant speed, gets you back any previously-milled threat, and has some pretty significant interactions with other powerful spells including the number one self-mill effect on our list 1
Kitsa has vigilance, prowess, and two abilities - you can tap the otter to draw a card and then discard a card, or you can spend two generic mana and tap it to copy an instant or sorcery spell you control, with the caveat that Kitsa needs three power to do so