The power level of the main devotion engines Master of Waves, Gray Merchant of Asphodel, and Fanatic of Mogis is high enough (when you have significant devotion) that it overwhelms the benefit of running multiple colors
Additionally, by paying one generic and one black mana and sacrificing an artifact, you can give target creature -2/-2 until the end of turn
Plastic cards offer the highest resistance
Sorcery Color tag templates(None) Mystical Tutor Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top
Both variants are covered in gold, but the Enchanted version takes things in a very Scrooge McDuck direction, tossing Prince John on top of a literal heap of coins
In all seriousness this might be the most comprehensive Pikachu guide Ive read, great job