The fact that its Blue fits the theme, but it also means youve got access to plenty of spells that will allow you to utilise this to either control the board state, your opponents hands, their library - or basically whatever else you want
What makes some of these Ultimatums so powerful is that they change the state of the game, often rapidly throwing you ahead of everyone else, and dont need too much setup beforehand
What do you do with a free creature
There are myriad creatures in blue and green that can function as effective removal
The Mindskinner Ten power on a 3-drop has to have a catch, right
When this Aura enters, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with this Aura." Return enchanted creature card to the battlefield under your control and attach this Aura to it