Wrath Potion

This is one half of a matched pair of damage buffs, and unlike the class-specific potions it lifts everything you swing, shoot or summon. Drink it beside a Rage Potion rather than choosing between them, since the two stack and cover the same fight.

The awkward part is the fish. Ebonkoi only bite in corruption water, so a crimson world either imports them from a second world or grows its own patch. Buy Corrupt Seeds from the Dryad once hardmode is running and she is standing in a graveyard, then seed a small pool somewhere far from anything you care about.

Keep that patch tiny and fence it with a material corruption cannot cross. An artificial biome that gets away from you will cost more time to clean up than every potion it ever brewed.