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Nelly Borca, Impulsive Accuser ($25 / 19.64) is in the Commander seat here

Waveskimmer Aven You need to consider how exalted is going to improve that creature when it attacks once you start paying 5 or more mana for these creatures

For just one white mana, you get to permanently remove a creature from the game

Fiery Justice Fiery Justice is a solid removal spell

Opalescence is clearly an enchantment deck build-around, which let you turn Replenish into not only a source of lots of virtual card advantage, but also a massive battlefield position that could easily dominate and end the game

That and other targeted removal goes at the top of the list, since one Doom Blade or Terminate now gets three creatures