Whenever a creature you control with power or toughness 1 or less dies, target opponent loses 2 life and you gain 2 life.
Arnyn is a mono-black aristocrats engine: flood the board with cheap and 1-power/1-toughness creatures and tokens, then sacrifice them en masse to drain each opponent for 2 and gain 2 every time one dies. You win by chaining death triggers through sacrifice outlets and recursion until the table is drained out, all while Arnyn's deathtouch lets it trade up and deter attacks. Turn to turn you build a token base, deploy a sac outlet, and loop bodies through it.
Each qualifying death is a guaranteed 2-life drain plus 2-life gain, so wide token boards translate directly into reach and lifegain stability.
Mono-black gives premium tutors, recursion, and removal, making the engine consistent and resilient.
Deathtouch makes Arnyn a strong defensive blocker that trades with anything.
Token and reanimation strategies naturally feed an endless supply of expendable small creatures.
Triggers only fire on creatures with power OR toughness 1 or less, so big-creature decks don't synergize and a board wipe of fat threats does nothing.
Needs a sacrifice outlet to be reliable; without one, drains depend on opponents killing your creatures.
Mono-black lacks built-in card advantage outside life-pay draw and can run dry without engines.
Graveyard hate and token hate (Cursed Totem, sac-stoppers) hit the core engine hard.