It asks that you play at instant speed so that it can play nicely alongside other possible instants
Overlord of the Hauntwoods Duskmourn MR Overlord Another solid Overlord from the Duskmourn cycle is Overlord of the Hauntwoods

Commander (1) Creature (23) Assaultron Dominator Brotherhood Scribe Curie, Emergent Intelligence Loyal Apprentice Red Death, Shipwrecker Steel Overseer James, Wandering Dad Nick Valentine, Private Eye Paladin Danse, Steel Maverick Rex, Cyber-Hound Synth Eradicator Arcade Gannon Elder Owyn Lyons Robobrain War Mind Solemn Simulacrum Whirler Rogue Liberty Prime, Recharged Sentinel Sarah Lyons Sentry Bot Shaun, Father of Synths Synth Infiltrator The Motherlode, Excavator Behemoth of Vault 0 Instant (8) Dispatch Swords to Plowshares Electrosiphon Thirst for Knowledge Crush Contraband Glimmer of Genius Unexpected Windfall Bottle-Cap Blast Sorcery (4) One with the Machine Austere Command Open the Vaults Wake the Past Enchantment (5) Overencumbered Nerd Rage Mechanized Production Vault 112: Sadistic Simulation Vault 13: Dweller's Journey Artifact (22) Everflowing Chalice Sol Ring Wayfarer's Bauble Arcane Signet Automated Assembly Line Expert-Level Safe Lightning Greaves Mind Stone Plasma Caster T-45 Power Armor Talisman of Conviction Talisman of Creativity Talisman of Progress Thought Vessel Brotherhood Vertibird C.A.M.P

Massacre Girl, Known Killer With Massacre Girl, Known Killer, you get to draw a card whenever your opponents creatures with power 1 or less die