Mox Sapphire is probably the most famous of the cycle and a staple of Vintage decks that, for the most part, use many blue cards to support Force of Will and other means of free protection, in addition to being the color of timeless staples like Tinker and Ancestral Recall
Hidetsugu Consumes All While admittedly narrow its application, Hidetsugu Consumes All can be a total blowout against many decks such as Hammer, Hardened Scales and to some extent Temur Rhinos
You could run something like Man-o'-War or Nekrataal to deal with problems your foe tosses out
The Indomitable is a 6/6, four-cost Legendary Artifact with Trample and card draw
If I'm making an effort to play more non-permanent spells, I should REALLY make an effort to play more 'Walkers, especially when they're perfect for the deck
Prices are updated based upon Pokemon Unified Minds listings that sold on eBay and other marketplaces