Equip Spells Similar to Continuous Spells, but must be activated by targeting a Monster, in which case it is said that it is equipped to that Monster
Demonic released
In the case of Urza, having him along with The Mightstone and Weakstone in play costs 8 mana total, not to mention the additional 7 mana to activate Urzas melding ability
However, it's the second ability that really stands out
While nothing beats the thrill of facing opponents in person, whether for fun or in competitive matchups, the reality is that sometimes circumstances don't allow for it, or you might be eager to try out new card combinations that you don't own

Aang's Iceberg Aang, Swift Savior Aboleth Spawn Accelerated Evolution Activated Sleeper Adaptive Shimmerer Ademi of the Silkchutes Aether Meltdown Affa Guard Hound Agent Venom Airtight Alibi Akoum Alchemist's Refuge Alexi's Cloak Alms Collector Aluren Ambrosia Whiteheart Ambush Gigapede Ambush Paratrooper Ambush Viper Ambush Wolf Amphibian Downpour Anafenza, Unyielding Lineage Ancient Stone Idol Angel of Grace Angel of Salvation Angel of the Dire Hour Animate Spell (playtest) Annie Flash, the Veteran Appa, Steadfast Guardian Appendage Amalgam Aquitect's Defenses Archangel Avacyn Archivist of Oghma Arlinn, the Pack's Hope Armaggon, Future Shark Armor of Thorns Ashcoat Bear Ashiok's Erasure Ashiok's Forerunner Asinine Antics Aspect of Manticore Aven Interrupter Aven Mindcensor Aven Reedstalker Avengers Assemble