It might seem like Blood Moon can serve a purpose against the secondary Mystic Sanctuary plan of a lot of these Arcums Astrolabe decks, but Cryptic Command makes that difficult
Reaper King (Classic Version)
While affinity for artifacts is the mechanic most will instantly think of when plotting how best to maximize the potential of Energy Tap, there are plenty of other creatures in and outside of blue that can easily be played for a steep discount
Theres incentive to play battles, as winning earns you XP, which helps you level up, which helps you open more booster packs, which helps you build better decks to win more battles
The next aspect to consider is the thickness
They love to kill creaturesAnowon, the Ruin Sage, Gatekeeper of Malakir, Ascendant Evincar, Butcher of Malakir, Vein Drinker, Vampiric Dragon, Drana, Kalastria Bloodchief, Guul Draz Assassin, Repentant Vampire, and Kalitas, Bloodchief of Ghet