Glint-Sleeve Siphoner

Two-mana black card-advantage creatures have always lived in the shadow of Dark Confidant, and this one answers the obvious objection to that card: the life loss is no longer involuntary. Bob draws you a card every upkeep whether you can afford it or not, flipping a fistful of damage off your own library. The siphoner instead bills you on a schedule you control, asking for two energy at your upkeep and only then trading a single life for a card. The energy is the clever part of the engine: you get one counter when it enters and another every time it attacks, and because the trigger fires on the declaration of the attack rather than on connecting, a blocked or chumped swing still pays into the meter. That decoupling from combat damage is what keeps the engine running when the board clogs up; you are stockpiling energy off attacks that never get through, then cashing it in on your own turn for exactly as much card advantage as your life total can stand. Menace helps the attack land more often, but the counters accrue regardless. The result is a card-advantage creature whose tax is paid in tempo and incremental life rather than in the lump-sum gamble of its predecessor, with the player, not the top of the deck, deciding when the meter runs.