In blue decks that arent running green especially, this is an easy include
One (1) Special card
Here are a few options that each one can search: Trinket Mage - Esper Sentinel, Sensei's Divining Top, Shadowspear Tribute Mage - The Soul Stone, Arcane Signet, Grinding Station Trophy Mage - Buster Sword, Extraplanar Lens, Simularcum Synthesizer Transit Mage - The One Ring, Roaming Throne, Iron Man, Titan of Innovation Tribute Mage - The Great Henge, Knowledge Pool, The Immortal Sun #3 - Harmonic Prodigy Harmonic Prodigy
There arent any golden rules for that and its very matchup dependent
The first of the two is epic, which sits between legendary and enchanted rares
Spend this mana only to cast an artifact spell or activate an ability of an artifact source