Lord of the Pyrrhian Legions — Whenever Anrakyr the Traveller attacks, you may cast an artifact spell from your hand or graveyard by paying life equal to its mana value rather than paying its mana cost.
Anrakyr is a mono-black artifact aggro/value engine: attack each turn and cheat out artifacts from hand or graveyard by paying life instead of mana, then convert that artifact density into card advantage, mana acceleration, and lethal damage. You ramp into a quick Anrakyr, swing, dump big artifacts (often expensive ones you couldn't otherwise cast) for life, and snowball your board until you finish with combat, big artifact creatures, or an artifact-fueled combo.
Effectively casts artifacts for free (just life) every combat, generating huge tempo and mana savings
Recurs artifacts straight from the graveyard, making removal and sacrifice synergies low-cost
Mono-black gives unmatched tutoring, life recovery, and reanimation to support the engine
Turns clunky expensive artifacts (Eldrazi-tier mana rocks, big bombs) into combat triggers
Engine requires Anrakyr to connect in combat, so he's a removal/blocker magnet
Life payment can be exploited by opponents and adds up fast in mono-black
No evasion or protection built in—needs equipment or auras to stay relevant
Mono-color means weaker interaction and no access to blue counters or green ramp variety