A bit too important for me to leave to the end, the Mightstone and Weakstone are two of the artifacts found by Urza and Mishra in the Caves of Koilos ( that is a card I use a lot in actual magic) and they fought over these for a good chunk of the conflict
The developers of MTG Arena said they decided against a disenchant system because it created feel-bad moments when people disenchanted cards they needed later
Players might initially pick tribes with high average mana values like Dragons or Angels or Sea Monsters (Krakens, Leviathans et al.), or pick commanders themselves that have a high mana value
Delver of Secrets remains a favorite archetype in the high-powered Legacy format, and its flipside, Insectile Aberration, is shown here as the upgraded Docent, and then, ultimately, the Final Iteration, completing the Delvers transformation from devious Wizard to all-consuming Insect god