Equip Serpent Spear when your hand is full but you're short on Attacks — it turns cards clogging your hand into a range-3 strike that reaches almost clear across an eight-seat table. Rebels swarming the Lord, or any aggressor sitting on a fat hand, want it most. Just remember it costs two cards per Attack, so it drains a thin hand fast — save it for surplus turns or the killing blow.
It pairs with Zhang Fei (Roar), feeding his unlimited Attacks from any two cards until the target runs out of Defense. Add Ma Chao (Horsemanship) and Red Hare to shrink distance and reach any seat, and it keeps Lu Bu (Peerless) — and anyone dragged into a Duel — stocked with Attacks to win the exchange.
It resolves as a normal Attack, so a saved Defense blocks it outright — Negate won't help, since it isn't a trick. Wear Eight Trigrams for a chance to auto-dodge and ride Shadow Runner to slip past its three-range reach. Best of all, it burns two cards per hit: stall the game, make them spend, then answer with a single Defense.