Massacre Girl Massacre Girl works as a very niche commander that extracts the full value from creatures that get counters when other creatures die (Slaughter Specialist) or benefit from the number of creatures that died in a turn (Bloodcrazed Paladin)
However, if you would like to give a "Venom" deck a shot, feel free to get some inspiration on the rest of the cards from my "Archetype Analysis: Venom" article on my blog, which you can find here:
Assault Beast X EARTH Level 4 [ Beast-Warrior / Effect ] ATK 1900 DEF 1200 You can discard this card to the GY
Once the board is open and Ruhan sufficiently suited up with our armory (Obsidian Battle-Axe, The Reaver Cleaver, etc.) and auras (Steel of the Godhead, Mantle of the Ancients, etc.), we can further ensure opponents are vanquished in timely fashion by copying our Commander via cards like Helm of the Host and Irenicus's Vile Duplication, which ignore the Legendary rule
Level 6
If that creature was an Angel, you get a number of Blood tokens equal to its toughness instead