If someone sends a massive attack your way, you can blank the whole thing for four mana
Black Well, its a good job Ad Nauseum is life loss, eh
While you might feel a bit limited with just mono-blue, this commander can churn through your deck or copy important spells once you resolve a couple of prowess triggers
Gaea's Cradle The best MTG land you can actually play An land only needs to produce two mana when you tap it to be, objectively, broken
It may be slow at 6 mana, but Archetype of Imagination can effectively make your fliers unblockable (reach aside) by hating on all your opponents' flying creatures
This combo-focused legendary creature rewards your spell casting by dealing one point of damage to an opponent with each instant or sorcery you cast and then refunding one red mana back to your mana pool