Obelisk Spider

The trick is the chain reaction the second ability builds out of the first. A 1/4 with reach is a defensive body that wants to block, and blocking is exactly how it triggers: deal combat damage to a creature, drop a -1/-1 counter, and the counter itself fires a drain that costs each opponent a life and hands you one. The same combat step that shrinks an attacker moves the game state in your favor on both axes of the life total. What elevates it past a one-shot is the generality of that second clause. It does not care that the spider put the counter there. Any -1/-1 counter you generate from any source, all at once, fires a single drain, so a sweeper or a counter-doubler turns the spider into a Blood Artist that reads off attrition rather than death. Four toughness is the reason this survives to keep grinding: it blocks most early aggression and walks away, then sits back as a reach wall while the engine ticks. It pays off a deck already speaking -1/-1 counters as a removal language, quietly converting every removal spell into incremental life swing. On its own it is a sturdy roadblock; alongside other counter sources it becomes the payoff that lets the whole subtheme close games.