The mana base needs a bit of an upgrade, even if that's just including a few more basics and fetches, such as Terramorphic ExpanseTerramorphic Expanse and Evolving WildsEvolving Wilds
10 Yzma, Alchemist It isnt always about the power plays and end moves in Lorcana
Since your core strategy will involve either directly sacrificing rats or using them to block opponents creatures and dying anyway, Voracious Vermin is bound to scale up in strength pretty quickly
[[Sephiroth, Fabled SOLDIER]] turns into [[Sephiroth, One-Winged Angel]], granting: Super Nova As this creature transforms into Sephiroth, One-Winged Angel, you get an emblem with Whenever a creature dies, target opponent loses 1 life and you gain 1 life. Whenever Sephiroth attacks, you may sacrifice any number of other creatures
From there, they can combo off with a commander like Urza, Lord High Artificer or Breya, Etherium Shaper to win the game via value, direct damage, Thassas Oracle, or any number of other infinite combos