Smelted Chargebug

In Commander, Smelted Chargebug slots into any energy-matters deck as an affordable enabler — the format's slower clock means its one-time cost reduction compounds across a long game, especially alongside commanders that generate and spend energy each turn. In Pauper, energy-based strategies are niche but real, and a commons-legal piece that refunds its own activation cost has genuine utility without demanding deck contortion. Legacy and Vintage are both legal but irrelevant here — Smelted Chargebug isn't touching those formats in any competitive configuration. Oathbreaker mirrors Commander's logic: if your planeswalker signature spell or activated ability runs on energy, this is a cheap, repeatable setup piece worth a slot.