Here are the general rules of thumb I follow when addressing this question myself: If my deck has green, the best mono green mana ramp spells are usually better than my multicolor options
Those are only the tip of the iceberg, and with payoffs like Disciple of the Vault or Nadiers Nightblade, being in monoblack seems less like a disadvantage and more like a brewing challenge for the ages
The subtle first edition stamp and shadowless border
Set: HeartGold & SoulSilver: Unleashed Type: Fighting Rarity: Common Retreat cost: Colorless,Colorless,Colorless
Colorless lands are easy to splash in Commander, but not so much in Limited
It will always double the number of Rats you have , increasing your board presence with one activation