Mindbreak Trap is a great way to put a stop to a counterspell war, an infinite spell combo, or just to disrupt your opponents plans if theyre casting a bunch of spells
Its partially because there are better things to be doing in mono-blue (if you want to focus on fast consistent wins, that is), but I do think Cosima can offer a lot, particularly if built around
Arahbo, Roar of the World If youre building around Arahbo, Roar of the World, youre doing cat typal
If the face-up Morph can legally be enchanted by the aura, it will continue enchanting it
Blue Makes Use of the Three Best Words in Magic on Candlekeep Sage An oft-quoted saying by players is that the three best words in Magic are "draw a card." Since blue is the best color at drawing cards, it only makes sense that the best blue background would do just that
Ignoble Hierarch: An incredible ramp creature for already powerful Jund (black/red/green) decks