Electrozoa

The energy counters here can fuel a payoff elsewhere, but by default they are the upkeep on the body itself. A 3/1 flash flier is aggressively costed, so the design attaches a self-imposed tax. The creature arrives with exactly two energy, and at the beginning of each of your first main phases it demands one back. Note the timing precisely: it untaps normally during your untap step, and only then does the trigger tap it down unless you pay, which leaves it upright and available through your upkeep for any interaction that wants an untapped creature. That gives it two turns of free attacks (or blocks, since flash lets you drop it in as a surprise flier before combat), after which the meter runs dry and the thing sits idle unless you feed it from another source. It is a battery that discharges into its own attack step, which reframes the card entirely: the interesting deckbuilding question is not what the 3/1 does but where the third and fourth energy come from, because a lone Electrozoa quietly stops attacking once its energy runs out. Slot it into an engine that generates energy incidentally and the tax vanishes; run it alone and you get a two-turn clock that goes dormant. The flash-plus-flying shell is the familiar tempo package (ambush a creature, hold up interaction, then swing), but the energy clause turns a clean evasive beater into a resource-management puzzle whose answer lives outside the card.