(It can't be blocked except by creatures with flying or reach.) Tap target creature
There are a lot of useful Rats you want to stick on the battlefield, and Swarmyard helps make your opponents require two removal spells if they ever want to take care of a Rat
The shaves to the typical manabase likely form some combination of Ancient Ziggurat or Unclaimed Territory for a Sunbaked Canyon, and possibly the Island for the Waterlogged Grove, but I will need to go into the lab to figure out the right formula
Archelos, Lagoon Mystic Brokkos, Apex of Forever Brokkos, Apex of Forever Damia, Sage of Stone Felix Five-Boots Glarb, Calamity's Augur Gonti, Canny Acquisitor Henry Wu, InGen Geneticist Indominus Rex, Alpha Kadena, Slinking Sorcerer Kotis, Sibsig Champion Kotis, the Fangkeeper Leovold, Emissary of Trest Maralen, Fae Ascendant Mimeoplasm, Revered One Muldrotha, the Gravetide Muldrotha, the Gravetide Nashi, Moon's Legacy Nine-Fingers Keene Otrimi, the Ever-Playful Rayami, First of the Fallen Sidisi, Brood Tyrant Sin, Spira's Punishment Teval, Arbiter of Virtue Teval, the Balanced Scale The Master, Transcendent The Mimeoplasm The Wise Mothman Volrath, the Shapestealer Vorosh, the Hunter Xavier Sal, Infested Captain Yarok, the Desecrated Zaxara, the Exemplary Zimone and Dina
Plus, 7 mana for a decent colorless board wipe isnt even that expensive, especially as there arent any color requirements here
