Undercity Sewers (Borderless): Murders at Karlov Manor Betrayers of Kamigawa you may reveal a Goblin

you may reveal a Goblin card from your hand

Flying Revenant's power and toughness are each equal to the number of creature cards in your graveyard

return target creature card with mana value 3 or less from your graveyard to the battlefield

Target spell or permanent becomes blue

Sacrifice Chromatic Sphere: Add one mana of any color

Undercity Sewers (Borderless): Murders at Karlov Manor Betrayers of Kamigawa you may reveal a Goblin({T}: Add {U} or {B}.) Undercity Sewers enters the battlefield tapped. When Undercity Sewers enters the battlefield, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)