Reservoir Walker

Five mana for a 3/3 is a rate no constructed deck pays on the body, and that inversion is the point: the creature is the smallest thing you are buying. What this Construct actually sells is a deposit into the energy economy, three counters arriving alongside a three-life cushion, packaged in a colorless frame that slots anywhere. Energy was the rare resource that lived outside the mana system: you could not tap a land for it or draw into more of it, so the live question with every energy source was the conversion rate between mana spent and counters banked. This one buys a clean, no-strings deposit at the cost of a body it will never earn back in combat, the kind of filler an engine wants when the plan is refilling the reservoir rather than spending the turn on tempo. The colorless artifact frame is the quiet design lever: it lets an energy payoff sit in a shell that does not commit to a color, which is exactly what a mechanic built to span multiple archetypes needs from its common-and-uncommon backbone. And the deposit is safe once it enters: the life and energy come from an enters trigger that goes on the stack and resolves on its own, so killing the creature in response still leaves you three counters and three life richer. Judged as a creature it is forgettable; judged as a battery with a 3/3 stapled on, it does precisely the unglamorous restocking work an energy deck was built around.