When Phylath dies, Pitiless Plunderer and Nim Deathmantle trigger.
Resolve the Pitiless Plunderer trigger, creating a Treasure artifact token.
Activate the Treasure by tapping and sacrificing it, adding 1.
Resolve the Nim Deathmantle trigger, causing you to pay 4 to return Phylath from your graveyard to the battlefield, and attach Nim Deathmantle to it.
When Phylath enters the battlefield, its first ability triggers, creating at least three 0/1 Plant creature tokens.
Activate Viscera Seer three times by sacrificing three Plants.
When the Plants die, Pitiless Plunderer triggers three times, creating three Treasure artifact tokens.
Resolve the Viscera Seer abilities from steps 1 and 7, causing you to scry 1 four times.
Activate three Treasures by tapping and sacrificing them, adding 3.
Repeat.
If you control at least four basic lands, this combo nets infinite Plant tokens, Treasure tokens and colored mana.
This loop transforms your basic land count into an unstoppable engine, relying on Viscera Seer to sacrifice your creatures while Pitiless Plunderer funds the resurrection. When Phylath, World Sculptor hits the graveyard, Nim Deathmantle steps in to bring it right back to the battlefield—provided you have the four mana needed to pay its revival cost. Thankfully, sacrificing the Plant tokens created by Phylath's entrance (along with Phylath itself) feeds Pitiless Plunderer to generate the exact Treasure tokens required to pay for the Deathmantle's trigger and net you infinite mana, scrys, and tokens along the way.